Why did the first man sin according to Maimonides?

2 questions that arose for me after rereading Chapter 2 in Part 1 of Teacher of the Confused.

1) If I understand correctly, according to the Rambam, man was created in the image of God, he is the intellectual power in man, and by this power man distinguishes between truth and falsehood. After that, man fell from this level of a being with reason and planted after his imaginations, desires, etc. If I understand what is told in Parashat Gan Eden as a story with a sequence of events (first man was a rational being and then he fell to become a being who pursues his imaginations), how could a man who is a pure intellectual being in the first place fall into this pursuit, since he should have judged reality correctly and not fallen?
One answer that comes to mind, along with a combination of chapter and part two, is that this is not an event with a chronological order, but rather a parable description of the essence of man, in which there is the male, who is the intellectual power, and the female, who expresses his materiality, and the snake, who is the power of guessing that misleads him. And if so, the whole story is actually a parable about every person from the beginning of man's creation, and there was never an act here that changed his essence, but that's how he always was.
2) My second question is about free will in man. It seems that as stated, man should strive to be a creature whose mind controls the imagination. Can such an ideal man have free will? If he is obligated in every situation to act according to his mind and according to truth and falsehood, doesn't this make the meaning of choice in man redundant? In my understanding, choice is something that stems from the fact that man has a value judgment on reality that is related to good and evil according to his perception, and therefore he chooses values ​​that seem good to him. Can a purely rational creature that lacks human judgment of good and evil have a choice?