I've seen this idea a few times in other entries, but so far this is the best execution. I was able to pick up on the controls almost immediately and the level design was fantastic.
The audio and art style weren't bad, but didn't knock it out of the park. That's my only real criticism and it can be forgiven for a game jam.
If you wanted to make this a full title, maybe add a story inspired by Alice in Wonderland? That scene where she needs to get small to enter Wonderland might work.