The music and the art are great, I like the character a lot!
The controls, however, are a bit lackluster imo.
For example: I realized how you programmed left / right, you're not moving your character on a fixed number / axis, you're adding a force on a key input, which means that if I spam A enough, I can skip almost the whole level and reach the flag by boosting the character with 100000 force :D
It also means that air control (controlling your character mid air) is not smoothed out, which is a big factor for me in plattformer games like these.
I also got stuck on the jump well (could not jump at all). If you work on the controls, this game could turn out to be one of the better ones here! :)