Very impressive, but short. How much space does a screen take you? If it’s a lot you could use some procedural levels to cut size and make it a lot longer.
If you’re interested in trying that, the obvious algorithm is to just make a row of platforms at random heights, with none raising higher than the character can jump. This can be done in a really simple loop (for x, if x > width: width+=random, for y, if y > height: fill) so it should be pretty small. Put an enemy every few platforms and whatnot. But that’s the most boring algorithm you could use, as well.
I feel that your most interesting screens are the 2nd and 3rd ones. There’s an old roguelike algorithm that you should be able to modify to come up with something like these. In it, you divide the screen randomly, adding a door between the halves, then divide the halves each randomly, adding a door, and so forth. I’m not sure how you’d modify this to be non-recursive, mind you, so fitting it in the space could be tough.
Either way, this is a very impressive game. Great job!