Definitely an interesting and a unique concept!
The camera's movement could be smoother, it moves weirdly when the player double jumps. The player's movement also gets weird sometimes, like the jump height is different so you have to try the jump again. You can also add a glow to show which enemy we are going to switch with on the next death so it is more clear. The game could also do with a lose condition, maybe you lose a live if you jump into spikes and don't have any enemy to switch with, and you lose when the lives are over.
I can see a potential game with this mechanic, I would love to see a full game which uses the death-switch mechanic to create interesting puzzles!