Impressive work for a first game!! It is a very fun idea that you should expand in the future :)
In case it helps, I would suggest leaving more empty space in the levels, specially in the first ones, where you want the player to perform jumps easily (without hitting the ceiling) and get used to the mechanics of the game. Also, if you keep only a few scales (say 0.5, 1, and 1.5, instead of steps of 0.1), you probably don't need the labels indicating scales, since it would be obvious from the size of the character and the objects. It feels more natural if you can convey an idea using graphics or storytelling rather than explicitly telling the player about it. Keep it up and congrats again! :D