Another perspective: Jazz pianist here. I looked at Mark Levine's book when I was in my early/mid 20s, by then I already knew everything in it - and I'd learnt almost all of it
from the music, from the greats. I don't believe in (theory) books, or teachers, really. I don't wish I'd read that book before I knew any of it.
I played classical for years as a kid, then played any songs I could get my hands on - folk songs, pop, Beatles etc. So I learnt basic chords and how they work by playing that stuff a lot. Then when I got into jazz, you learn by listening and transcribing. Transcribing tunes, solos, chord voicings, anything. All different instruments. I've transcribed piano, trumpet, sax, guitar, bass, drums.. and Indian classical, funk, reggae etc. Anything you hear and like but don't know what it is, transcribe it, and learn to play it yourself. (If it's simple enough, you don't need to write it out) You learn a lot of things by doing that. There are books of transcribed solos, I think they're absolutely worthless. Do it yourself. Besides that, books of songs, solos etc always have mistakes, sometimes a few, sometimes thousands. I've written out orchestral scores to play on piano, studied those. I studied/played/sang Debussy's opera for over a year, that felt like a complete musical education, a lot of it is simple combinations of notes. In my 20s I learnt a lot about what pianos can do by playing a lot of piano pieces by Debussy, Ravel, Rachmaninov etc. Also playing other instruments is good - I've spent a fair bit of time playing drums, bass, guitar, trumpet, trombone, clarinet, etc. Also learning who the great musicians are is invaluable, so you can find who appeals to you most. Check out a lot of different stuff. Study, analyze, learn from the music you listen to and love. All that is so much easier since the internet! (I started in the 80s) It should all be a great joy. I enjoyed every minute of it.