Some literacy critics have defined tragedy as “the downfall of a hero.” would aristotle agree? how might he revise this definition?

Aristotle would basically agree, but his definition of Tragedy was much more complex. Aristotle's idea of tragedy centered more on what the audience got out of the play than the actual character's ending. The audience should be feeling pity and fear (based on the main character who should be morally sensible and somehow relatable to the audience), and then be able to experience a release of emotions that leaves them feeling refreshed and cleansed.