No other film franchise had ever attempted to do what the Harry Potter movies did.
Because no movie had ever done anything quite like it, certainly not to that extent, no other actors had ever been through what Daniel Radcliffe, Emma Watson, and Rupert Grint had.
Harry Potter and his friends are introduced to us as 10-year-olds and by the end they were all adults.
Eight movies were produced over the course of about a decade, telling the complete story.