Thank you, I appreciate your help. There are gamepad bindings as well but WebGL can be fickle. They are working now from my side, but I can't guarantee they will work for everyone. Still, I put the bindings in the description on the controls.
I also want to let everyone who gave feedback on the difficulty I have made some other changes already:
Reordered the levels by difficulty, added a couple more levels to explain the dash mechanics (want to make more tomorrow), and added a key to skip levels if the player gets too stuck so everyone can enjoy the full game.
P.S. When I play-test I use the shift and space bindings myself now. They felt awkward to me at first but I get the appeal now : ).