Thank you for the responses and for your willingness to enter into the discussion.

I think that there is דווקא a very clear and well-reasoned conception here of his position.
The whole first part of his words is principled and a priori, since all his words come to explain the Talmud in Chagigah 3 (“the masters of assemblies,” etc.)
— which does not distinguish between periods and presents dispute as an ideal notion from the outset (“all of them from one Master,” etc.).

At the beginning of his words he states emphatically, and without any qualification about periods:
“for it is impossible for the opinion of the sages to follow one single path,
and it is impossible that there not be disagreement among them according to the way they differ in their intellects.
For with regard to every single thing, it is impossible that there not be more than one aspect to that one thing.
For even if the thing is impure, it is impossible that it not have some aspect tending toward purity,
and likewise, if the thing is pure, it is impossible that it not have some aspect of impurity.
And human beings differ in intellect, and it is impossible that all human intellects should proceed in one single way…”
(and he is certainly hinting at “just as their faces are different…”)

And later in his words he expands on the complex reality of the world
(the medieval scheme of the compounds of the four elements, etc.).

And he goes on to state:
“And you will not find anything absolutely simple.
So too in Torah there is nothing completely impure that does not contain some side of purity, etc.
And when one person studied some matter… he stated one aspect according to what he is, and the one who says impure also stated one aspect.”

Even more extreme are his words in his homily on the Torah, where he interprets in a similar way the declaring of the creeping creature pure on the basis of 150 reasons, etc.
(which seemingly certainly does not belong to the possibility of dispute).

Therefore, I understood (mistakenly, apparently) his words regarding the dispute of Beit Hillel and Beit Shammai as meaning that since ostensibly we do not know of dispute beforehand, then in order to disabuse us,
so that we not think that there is here a fall from “the higher level” of the complexity mentioned above, it says “these and those…”
And indeed, on a second reading (in light of your comment), I agree that he does seem to be speaking here about, ostensibly, three stages in which there is a decline from a state with no dispute to a state of disputes, by way of the intermediate stage of “these and those.”

But the question returns to its place: how does what he says about decline fit with everything he said before?
How did the a priori complexity in reality itself — as he describes it — make it possible that there was no dispute at first?
And what is the decline after the disputes of Beit Hillel and Beit Shammai?

And again, thank you, and happy holiday.

That is exactly what I was talking about. The difference between stage 2 and stage 3 is not defined, and it is inserted artificially even though there really is no difference. His wording implies that in stage 2 there was a situation in which there were two differing opinions, each of which was a full truth. And only in stage 3 did each one hold only a partial truth (one facet of the complex truth). But then it is unclear how, in stage 2, there could be two disputing opinions each of which holds a full truth (“the words of the living God”). Maybe the truth split into two truths, each of them complete (because there is no one single correct answer). And in the third stage they already break truth down (perhaps each of the two full sides) into its components, and no one has the full truth in hand.
Let us take as an example the Talmud in Gittin 6 regarding “he found a fly” or “he found a hair,” where it says there “these and those” (though not about Beit Shammai and Beit Hillel, contrary to what the Maharal wrote, that this was said only about them. That is true in Jewish law, but not in aggadic literature). One could perhaps argue that at first there was no dispute and everyone knew that it was a hair. Afterward the truth was lost and two opinions arose: a hair or a fly. At that stage each opinion is an absolute truth, because a case like this, in principle, could have blown up either over a fly or over a hair (in practice only one of them actually happened, but what matters is the principle and not the factual question of what actually occurred). And in the third stage a synthesis was already formed in which the fly and the hair together caused the blowup, but here there is a dispute in which one thinks it was a hair and the other thinks it was a fly, and therefore both hold only a partial truth (because the full truth is that both caused it: he found a fly and did not object; he found a hair and did object. The accumulation created the blowup).
But that really sounds to me like unnecessary pilpul. The insertion of the intermediate stage is done only because of a homiletic idea that there cannot be a direct decline, and now one has to define that stage (without much success). I don’t think there is any point to it.