It's a really cool concept, and overall it's executed really well, but as with any jam game, I have a couple complaints:
1) I thought the pacing was a little slow. To be fair, I usually don't like games as much where you have to wait for a slower character to move, but maybe increasing the movement speed by just a little bit could make it a lot better.
2) This is the main one, when you place a checkpoint, it seems like the player always goes in the same direction after respawning. I feel like the direction should be based on what direction the player is going when they die. That would not only be much more intuitive, but it will also make it easier to develop more interesting puzzles, since you could use that as another challenge for the player.
Other than that though, it was a really cool game. The sfx and music were really nice, I thought the art was done well and the core gameplay was interesting and well polished.
(Also if you could play my game as well I'd appreciate it)