Really sick game! Definitely invoked the Getting Over It "I'm going keep trying until I beat this" in me.
If feedback is welcome: I'd recommend looking into a technique called Coyote Time, and making gravity stronger when you're falling than when you're jumping, both of which can help the movement feel smoother. There's a cool "interactive video essay" you can play that demonstrates the concepts: https://gmtk.itch.io/platformer-toolkit