A lot of levels for such a short jam - impressive! I had fun with this one and enjoyed the growing and shrinking mechanic. I think there's a lot of potential for things you could do with it.
There was really only one gimmick you were working with here besides growing/shrinking for jump height and fitting through passages, and that was the buttons to open/close pathways. I'd recommend introducing more puzzle elements so you have more things to design with. Timed buttons, blocks you can break by growing, blocks you can push around by growing, etc. There's a lot you could add!