Yo that song is a jam! It gets me into a thinking transic vibe. Loops really well too.
For platforming I personally preferprefer my horizontal velocity not to be slowed that strongly when in air. And my jump to be a bit higher to make platforming feel better and also easier. Since the focus is not on tight platforming.
I had problems figuring out how to move the blocks. Yep I didn't read the wall of text controls :) To make it intuitive you can indicate the direction the block would move if I press lmb, with the mouse becoming an arrow pointing in that direction.
Once I figured that out it become a lot more fun! Before I was struggling with that while really digging the puzzles that you created with that. They are really smart and have multiple solutions. I really like that for puzzle games. Well done!