Harry is only considered so great because he is the only one who has ever survived once Lord V decided to kill him. In the books it's made clear that he's not the greatest, especially at the "book learning" side of it. What makes him great is that when faced with great adversity he has the ability to think on his feet and do the best he can.... let me find a quote...
when speaking of what it is like to face Lord V, Harry says, "...but all that stuff was luck--I didn't know what I was doing half the time, I didn't plan any of it, I just did whatever I could think of, and I nearly always had help... I didn't get through it because I was brilliant at Defense Against the Dark Arts, I got through it all because--because help came at the right time, or because I guessed right--but I just blundered through it all, I didn't have a clue what I was doing... You think it's just memorizing a bunch of spells and throwing them at him, like you're in class or something? The whole time you're sure you know there's nothing between you and dying except your own--your own brain or guts or whatever--like you can think straight when you know you're about a second from being murdered, or tortured, or watching your friends die--they've never taught us that in their classes, what it's like to deal with things like that--and you two sit there acting like I'm a clever little boy to be standing here, alive, like Diggory was stupid, like he messed up--you just don't get it, that could just as easily have been me, it would have been if Voldemort hadn't needed me--"
Harry knows he isn't the greatest wizard out there. It is his ability to love despite all he's been through, his bravery in the face of adversity, and his willingness to sacrifice to save those he cares about that makes him what he is. He is only famous because he escaped Voldemort as a baby.
Jackie