Good core platformer here, I liked that the "endless" mode was like a whole 2nd game in there!
I did struggle a bit knowing what objects were just decoration in the background and which you could jump on. For example, in level 1 there's a crate you jump on, but then later there's another crate that looks identical that is in the background.
Another thing to consider is to make the camera look ahead when moving fast/falling, instead of trailing behind. Since it follows behind I had to make a couple jumps with a blind landing and died from an enemy I couldn't see.
Thanks so much for participating in the Jam!