I dunno. I feel like if I handed D&D to a relatively nerd-knowledgeable person and said, “List its influences,” Harry Potter wouldn’t be the first thing that popped to mind.
- Where are the teenage angst mechanics?
- Where are the arbitrary but super important divisions into houses? (Tribes, schools, castes, whatever.)
- The sporting event that takes on outsized importance in the characters’ lives?
- The division between the magic-users and the muggles?
- The secret world that is hidden just down a diagonal alley from the normal world? (D&D has basically zero Hermetic or esoteric beliefs within it, because none of the occult/magic stuff in D&D is secret!)
For influences on D&D, I could definitely see someone say “Oh, it’s like (video game X)” or “(board game Y)” or even “(those old books from the ‘80s and ‘90s by Feist and Eddings)” [which would be to mistake the things that were influenced BY D&D for the things that influenced UPON D&D] [although of course at this point it’s an ouroboros eating its own tail].
I’m now curious if a serious market research company ever ran an open-ended “list all the things that remind you of D&D” survey what it would reveal. My money is that Harry Potter would be barely a blip.