Well done - Your concept is clear and while the game was very difficult, I think it met the GameJam criteria spot on.
I suggest you play with your physics a bit more, the jumping is quite difficult. I'd also suggest some "key colors" so that the player knows what is "safe" vs. "bad" - I died a lot on level 2 because I didn't know that the Yellow platforms were safe and the orange ones weren't.
Great job !