This is really interesting and well-written!

I think the line that starts "And how could he ignore the humans" should end with a question mark, since it's phrased like a question.

I liked seeing the Marauders, though it seemed a little strange to see their real names used in narration when Firenze wouldn't have known them. I guess it depends whether this is third-person omniscient or third-person limited point of view.

Overall great job on this!

Interesting idea! I particularly liked the musings on Dumbledore.

“Bane liked to prove his point by comparing centaurs to the Hogwarts groundkeeper, Hagrid.” should that perhaps be “comparing humans”?

The end was very good too.