Usborne Books also has a great set that graduates in difficulty. It's called My First Library https://www.usa4books.com/products/usborne-books-uk-books-my-first-library-50bks

Chiming in for others who may find this post down the road (as I did). One of my favorite literature groupings we did in my 12th year high school english class was Hamlet, Waiting for Godot and Rosencrantz and Guildenstern are Dead. I will concur that the movie (with Gary Oldman) is wonderful. Anyway, I would highly encourage including Waiting for Godot as it very much enhanced the reading of R&G (Stoppard uses the two-man absurdity as a template for R&G). R&G was of the highlights of my AP literature class that year!

The 11 Modern classics link from the OP is broken, here is the new link: https://www.today.com/popculture/modern-classics-11-novels-belong-classroom-1B5527101