I liked the art and the presentation - even though you didn't make it, the game looked good and that was a good design choice. The sound was pretty good but the music didn't really fit.
It was pretty frustrating once you got to the third level. I liked the idea, but I would have preferred a way to lock maybe the player cat in place by something like holding space bar for a short second or something, which would have allowed greater fidelity in the platforming. Controlling two characters is always a risk to the player because it's easy to get annoyed. Coupled with the brutal spike hit boxes, I must say I did not feel like I wanted to continue this one after a few retries.
With that said, there is a very interesting mechanic here that is definitely worth exploring. Platformers are notoriously hard to get just right (as GMTK Mark Brown himself stipulates in his videos), so it's unfortunately very easy to make it too hard. I don't think you are too far away from getting it right at all!
Great work and an interesting take on the theme!