Wow, thank you for the extensive review. I am surprised I was able to hammer all these levels out in one day...
I've definitely have gotten a lot of experience in making game jam puzzle games, and I've mostly learned that making something simpler is most of the time going to be better. I also got pretty lucky with this mechanic, since it worked very well within a puzzle setting. You know you got a good concept when making levels isn't too hard. But, I was scraping for some ideas near level 14 and 15.
I love your idea of changing effects and sounds when the player is different sizes, and I'm honestly surprised I didn't think of it, since I made the ballista sound change pitch depending on size.
I do plan on having at least a post-jam update, there are a lot of small bugs that can really effect the game experience.