Can someone suggest some textbooks to learn game design from? I've been reading Jesse Schell's "The Book of Lenses".

I've read a lot of books on game design, and there are only two of them that I'd recommend.  You're already reading one of them.  The other one is "Game Feel: A Game Designer’s Guide to Virtual Sensation" by Steve Swink.

Hello,
Deep, theoretical dive into the structure and meaning of games
Great for understanding why games work.     

e-zpassnj

Best Regards

This page has a pretty in-depth compilation of suggested books for game designers, even segmented by specialization: 

https://indiegameacademy.notion.site/Game-Design-Careers-4a1a7a6bc3c74e60ae228369b5dd5eb0