Have you actually gone back and read any of the copious amounts of ya books?

Off the top of my head – go and reread a Goosebumps book. They are super simple. HP is downright shakespearian compared to them.

Hardy boys, tom swift series (80s/90s versions) and countless other one shot books that I can barely remember are all super simple too.

Yes, there are always outliers like Redwall but when compared to the whole HP was well written regardless of the trash person who wrote them.