See briefly here regarding your question:
https://mikyab.net/%D7%A9%D7%95%D7%AA/%D7%94%D7%90%D7%9D-%D7%94%D7%9E%D7%95%D7%A1%D7%A8-%D7%94%D7%95%D7%90-%D7%94%D7%95%D7%90-%D7%94%D7%94%D7%AA%D7%92%D7%9C%D7%95%D7%AA

I think my question does not come from a place of skepticism. It is a problem of definition and identity between the biblical Lord and the experience the prophet undergoes.
In other words, the problem here is more than just inner conviction. The prophet did not learn in kindergarten what the Lord looks like and what He sounds like. The teacher did not point at Him and say, look, "this is the Lord and this is not the Lord." So on the face of it, it seems that the prophet defines this experience as the Lord on his own initiative. It could be that if another person were to undergo exactly the same experience, he would define it as just a daydream or a hallucination.

Is it possible that the prophets did not experience revelation, and only made use of this phenomenon, which was so widely accepted then, in order to convey their message?

Everything is possible, but the Torah itself speaks of prophecy and of the Holy One, blessed be He, revealing Himself to them. Therefore the burden of proof is on whoever claims otherwise.
In the link above I commented on the prophet's self-certainty. The fact that he never experienced something before does not mean he cannot grasp it. On the contrary, the doubt about his experience stems from the fact that you have never experienced such a thing, and therefore you do not reach the certainty that accompanies it. Like a blind person wondering about the reliability of the sense of sight.
And in general, previous experiences also cannot solve the problem, because they too began with a first experience, and if you cannot trust that one, then not the second either, and so on. Experience does not solve the problem you are raising, if there is one.

When a blind person opens his eyes, someone will need to point and tell him, "this is the color red and this is green." It is a matter of definition. So too when someone undergoes an experience in which he hears a voice or something else, it cannot be that he decides on his own that this is the same experience Moses our rabbi had.
If we believe that the prophets were upright human beings, it is preferable to say that they had no revelation of that hallucinatory sort at all. Rather, they used God in order to convey a message.

Why can't the Holy One, blessed be He, tell them that this is prophecy? What is the meaning of this insistence? I am baffled!!

Attached here is a Hasidic teaching from Rabbi Mendel of Rimanov (Torat Shimon, parashat Vayera, Devash HaSadeh, section 73).

The teaching deals exactly with the above issue—how Abraham our forefather knew that the revelation to him was from the Holy One, blessed be He Himself. The question is explained well, but I do not understand the answer. I would be glad if you would offer your opinion.

"And Abraham said to his young men: Stay here with the donkey, and I and the lad will go yonder; we will bow down and return to you."
It is known from all the holy books the greatness of the obstacles that Abraham our forefather had then, at the time of the binding—briefly, he had then all the obstacles that can exist in the world, for not for nothing has this trial stood for us from then and forever, to the end of all generations, and by its merit we are saved from all kinds of calamities, and every year our sins are atoned for.

And certainly Satan then used all kinds of schemes that it was possible to use in order to prevent him from the commandment of the blessed God, and our father Abraham, peace be upon him, in the great warmth and burning enthusiasm, with a great and terrible fire burning within him to fulfill the will of his Creator, blessed be His Name, paid no heed to all this, overcame everything, and went with great joy to offer up his only son.

When Satan saw that after all his toil and effort he had not succeeded, he tried one more tactic: perhaps he would catch him in this matter and bring him down, Heaven forbid. He appeared before him as a decent and righteous man, coming toward him and greeting him lovingly, as was proper, and asked him: Where is the master going? And he would answer: I am going to do the will of my Creator, who commanded me to slaughter my only son. And he would answer him: Happy are you, Abraham, that you are going to do the will of your Master, especially in such a great matter. Go in peace. But tell me, my friend, how do you know that it is indeed the will of the Holy One, blessed be He, to slaughter your son? And Abraham our forefather, peace be upon him, would answer him: I myself heard from the mouth of the Holy One, blessed be He: Please take your son, etc.

Then the aforementioned man said to him: Happy are you—certainly you merited a great thing, and not every person merits hearing words from the mouth of the Holy One, blessed be He Himself. Even so, I will not refrain from revealing to you what I heard and received from my rabbis: not every person merits hearing speech from the mouth of the Holy One, blessed be He, and even if he does hear, he should not rely on it at all, for perhaps it is, Heaven forbid, from some other side. Rather, only one who knows about himself that he has already corrected all his sins, especially the sins of youth, and has in him no sin or iniquity at all, like an angel—such a person can be sure that the glory of the Lord truly spoke with him. But one who is still uncertain whether he has already corrected the sins of his youth in every way—Heaven forbid for him to regard such speech as described above. Therefore, examine for yourself where that speech came from.

When Abraham our forefather heard this, he trembled greatly, for because of his great humility and lowliness he was concerned about those words, in the way of the righteous. And by this tactic Satan almost caused him to fall from the great joy and enthusiasm he had then. Immediately he strengthened himself and said: Heaven forbid that anything in the world should stop me from my service, even though it is true that I have still not corrected the sins of youth.

And this is the meaning of "And Abraham said to his young men"—that is, he said to his sins of youth, "Stay here with the donkey," with his materiality; "and I and the lad," that is, I together with my son Isaac, "will go yonder, and bow down, and return to you"—I promise you that I will come there to the great level of bowing down in great submission, and then I will return also concerning you. But for now, there is nothing in the world that will stop me, Heaven forbid. And he went with great joy to fulfill the commandment of the blessed Creator."

After Rosh Hashanah we understand that God is transcendent—"Holy, holy, holy"—
and for Him to reveal Himself to human beings contains something so immanent. It is hard for us to grasp this after the holiness of the day, because He is awesome and fearsome.

Of course there is no answer here. He simply left the obstacles with the young men and everything is wonderful. Cheap Hasidic one-liners.

I do not understand how we know that the prophet is not exaggerating and "cutting corners." He imagined/dreamed/invented and convinced everyone that the Lord spoke with him. Who says that he himself was necessarily convinced of it? And likewise regarding the revelation at Mount Sinai. How do we know they were so completely convinced, one hundred percent, and at a level at which one cannot be mistaken, like a sighted person versus a blind person? Where exactly is that written? And perhaps the sighted person can also lie and claim that he sees a flying hippopotamus playing a darbuka? After all, he sees, and the blind person has to believe whatever comes out of his mouth… I am not a skeptic either, but that does not mean I am obligated to believe everything I am told.

You truly are not obligated. We're done.

There is no reason that a normal person surrounded by crazy people whom God speaks to (false prophets) should believe that the voice he hears is God Himself speaking to him and not to others. A reasonable person would tell himself that this voice he hears or this experience he is having is just a hallucination.
And therefore the only reasonable interpretation regarding the true prophets is that God did not speak to them, and they merely used Him because in those days people listened only to those whom God spoke to.

And the reason for the insistence is that I do not recall God speaking to me or to anyone else I know.

Has God spoken with the honored Rabbi?

How do you know? Maybe He is speaking with me under the username Zerubbabel…

Today it is possible to examine metaphysical experiences such as clinical death as a hormone secreted in death and birth, called ketamine. Moreover, today it is even possible to undergo transcendental experiences in laboratories by isolating certain hormones. When we are aware of the way we experience things, it is hard not to wonder about the prophecies of those people.
What I mean is that no matter how powerful the event is, as long as it is individual, one cannot know whether this is revelation or hormonal dysregulation.

Correct. Today it is also possible to create visual illusions. By the same logic, you should not trust sight either. My assumption is that as long as there is no indication that this is an illusion, we are dealing with cognition. Of course, each case is judged on its own merits, and each person according to his feelings and the circumstances.

Zerubbabel, this is basically the power of mass testimony. How do we know that we are right and the crazy person is the crazy one? How do we know he isn't right and all of us are mistaken?

It only remains to note that prophecy ceased exactly at the time when it more or less ceased among the other nations too… [aside from exceptional individuals like Jesus and Muhammad. Once every king had in his court a whole gang of prophets and various dream interpreters].