I ask forgiveness for the bother.
But if this is, in some sense, from Heaven, then it seems clear enough to say that Torah written through divine inspiration is what is meant by "from Heaven" in the Talmud in Sanhedrin. [That is Tosafot’s answer in Megillah 31b, and the Maharsha explains them that way there.]
So if Tosafot write that divine inspiration is from Heaven, even though I don’t know exactly what it is, one can rely on them, no? And after that no difficulty remains [divine inspiration = from Heaven]. There’s no need to say the Rabbi’s answer there that this is on the normative plane. I don’t understand why the Rabbi needs to get to that. What did I miss?

I don’t understand what here still requires explanation. When people say that everything was given at Sinai, the meaning is that it was given at the Revelation at Sinai by the Holy One, blessed be He. That is not factually correct, because Moses formulated it (at a later stage, close to the entry into the Land). Rather, he formulated it through divine inspiration. Therefore one cannot say that everything was given at Sinai, except in the normative sense.
That’s it. I will not answer further, God willing.

I really apologize for the bother [the Rabbi does not need to answer]
But it doesn’t say in the Talmud in Sanhedrin that it is from Sinai!!!!
It says that it is from Heaven, and Tosafot answer this by saying it was through divine inspiration.
In short, where does it say that it is from Sinai????

From Heaven means from Sinai. The belief that Torah is from Heaven means Torah from Sinai. Also, in the Talmud in Makkot it says, "The 613 commandments were said to Moses at Sinai." And Maimonides already addressed this in Principle 1 of Sefer HaMitzvot (and see also Nachmanides’ glosses there).

It is clear that Tosafot hold that from Heaven is not the same as from Sinai.
Also, what the Rabbi brought from Makkot—I didn’t understand what the proof is for our issue, since the commandments were said at Sinai, but the writing of the Book of Deuteronomy was only through divine inspiration. And what the Rabbi wrote: "And Maimonides already addressed this in Principle 1 (and see also Nachmanides’ glosses there)"—I didn’t understand. Does Maimonides prove that from Heaven means from Sinai? Or is Maimonides discussing the 613 commandments?
In any case, is there proof for saying that from Heaven means from Sinai?

This is to assume a premise [from Heaven = from Sinai in the language of the Holy One, blessed be He] and raise a difficulty [but it is written in Moses’ language].
It is preferable to say like Tosafot and the other commentators [who are qualified to say that divine inspiration is from Heaven and not from Sinai, but rather in Moses’ language,] and then there is no need for questions and answers. What is wrong with that???

In any case, it is clear that this is Tosafot’s view and this is the explanation. But what did the Rabbi mean to bring from Maimonides? It’s just important for me to know.

Why isn’t the Rabbi answering?

I answered what I had to say.

Thank you. And sorry for the bother.