I acquired my aversion to modesty before reading your stuff, and I seem to identify that "thing", whatever it is shared by you and Harry, as "awesome" rather than "arrogant".

You're acting too big for your britches. You can't save the world; you're not Superman. Harry can't invent new spells; he's just a student. The proper response to that sort of criticism is to ignore it and (save the world / invent new spells) anyway. I don't think there really is a way to make it go away without actually diminishing your ability to do awesome stuff.