The graphics is certain the highlight of the game. The idea of having two characters at different scales is interesting, but I don't think it is affecting the gameplay of the game significantly.
The movement of characters is rigid, it should to be more polished considering the duration of this jam. At the beginning of the game, the player is still trying to get used to the controls, the we should fell off quite often.
The levels are getting more interesting as I get into later levels as more machansims are introduced. The earlier level are honestly kind of boring, especially considering they are pretty large. I think you should avoid long levels at the beginning due to the control problems I mentioned above. Players often fell off the platform and have to restart the long level. If this happens many times, players will get fraustrated and quit the game, which is sad because they will miss the more interesting content later.
I have having similar problems when it comes to level design with my game. At first I always want to make large levels. However, I realized that these levels are often repeative and boring. I think for puzzle games, smaller and delicate level usually better. If you are interested in my game, please go check it out.