I think one of the main reasons hp blew up is because every book covered one school year and most books were coming out once per year. So for example when I was 12, harry potter was 12 too, same at 13, 14, etc. We aged at the same time. I remember finding him relatable when he was too shy to ask a girl out in the fourth book, you know, generic teenager stuff. I also remember reading the first one when I was fourteen and I was kinda bored of it because I was basically too old to read it.

I don't understand how anyone can get into these books without being hp's age, but for me and everyone in my year it was pretty easy.