Not Harry. Beatrix. Project Gutenberg has a nice selection of B.P stories, with pictures.
Beatrix Potter would get my vote as Best Childrens Author Ever. Her characters are fluffy, but her world isn’t: there’s adventure, but also danger. I think this is better for children than cosy ‘WInnie The Pooh’ type stories, although I remember I found some Beatrix Potter a little scary…
Reading the line ”But Nutkin was in his waistcoat pocket” in a whisper can make still me shiver.