Great puzzle mechanics, I really enjoyed playing it.
Sometimes I wanted to push past my dead selves, would be annoying
I was annoyed with the reset screen every time I reset, but only at the end of the game did I see that there was a way of disabling that. A problem with the reset screen is that it says you've failed the level, which is pretty negative for just trying to restart.
Graphics design is pretty nice (menu etc.) but visually things can definitely be improved, even if you're not going to use any extra sprites. Having shadows and an animated jump (i.e. stretch when you jump) would definitely help. Also landing & jumping effects.
Going down on the elevator things would put you in the air repeatedly which didn't feel great, should probably stick to the surface when you're going down.
Overall was a good game and would love to see it with some more polish