Solid physics engine. There's potential for enemies who can't kill the player, no doubt. Using them as platforms or trapping them in puzzles, for example. I actually don't mind the jump, and the new boxes that appear really help make the platforming standout. Plus the enemies look like Metroids, so that's cool. Catchy song too!
Now my criticisms. The stars are hard to pick up for some reason, and restarting the level doesn't reset them to zero. The perspective switch doesn't feel like a perspective switch since in practice it only makes boxes materialize or dematerialize. Enemies are trapped by them too, after all. Also, sound effects are desperately needed. I also noticed some grays in the palette which goes against the jam's theme.
For a level one, it isn't half-bad. You did a solid job with the small amount of allocated time and the foundation has a lot to potentially work with.