Definitely the best game I've played this jam! You've definitely got yourself a full game concept here, I'd love to play a full version of this!
The controls are tight, the hitboxes are perfect, the level design is great!
Your "use" of the limitation is a little cheeky. It feels like multiple levels even though you are techinically "building" the one level. If you had had the frog zip back to the starting position and the new level pieces traverse in then it would have served to make it feel like the one room perhaps? As it stands I think it's basically 8 levels haha
Also for accessibility reasons the bg should be disable-able.