Nice and unique idea! I liked how it used a limited amount of colors, and the colors you used reminded me of old parchment paper. The art is kinda cool, but the pixels aren't uniform (the same size), which gives the game a hastily crafted vibe. I would recommend creating all of your assets near each other on the same canvas. The movement felt awkward, too. I can't put it into words, but it just did not feel nice to control, and I kept landing to places where I didn't wanna land at. I recommend the next time you make a platformer, to change and tweak any issues with the movement immediately, as you could get used to them and not realize that they are any issues.
Other than that, nice job!