Question

Aristotle said,"Man is a social animal ". change the narration

Answer 1

aristotal said that man is a social animal
this sentence not much changed because it is universal truth

Answer 2

Q. Aristotle said,"Man is a social animal ". change the narration

 Answer :- Aristotle said that Man is a social animal.

Now, why we have not changed the speech

So,
When the reported speech  is a habitual or universal truth  or a fact , then we do not change the narration.

In this sentence, it is a habitual or universal truth so reported speech remains the same.