Your goal of making a game that looks good is achieved. Visually the only thing I'd want to see if a bit more interesting background besides one colour, some screen shake, and some particles. But those are all small details, not needed.
The timer for the levels felt a bit long. When in doubt for a game jam game - make it shorter. It seems counterproductive because you want players to get more value, but short and sweet is always better for these types of things.
Good job!