Awesome platformer! With the shadow mechanic and the carry mechanic I can see a great puzzle platformer here. One thing I would recommend is to look into this twitter thread by the creator of Celeste. He talks about different game-feel things that make a platformer character super satisfying to control. It may not have been reasonable to add these all for a jam but I think it's definitely worth a read for anyone developing a platformer. Great game, I had tons of fun playing it!
https://mobile.twitter.com/MaddyThorson/status/1238338574220546049