This was really cool, you managed to fit a surprising amount of levels into this despite the time limit, which is really impressive. The art style is very clean and pleasant too, although I think some of the platforms look a bit too much like background elements (One of your screenshots shows what I'm talking about).
It has some rough edges though. I've never been a fan of 2d platformers like this where you have very little air control but then also have to make very tight jumps. There were a few points where the levels felt kind of unpolished too (Which is kind of expected since you made so many), like jumps that are a lot harder because of how easy it is to bonk your head or how the balloons in the skyscraper level don't respawn if you fall and need to get back up again.
Overall you did a good job though! It's a very solid Mario Bros style platformer.