I wonder why the tracks are so short, maybe to avoid some desync issues? Also, the control scheme really goes against learning the game. Maybe using amy set of 3 keys that are already vertically aligned would make the game may times easier. To help the player more, just slap the button name to the lane, write [space], [s], [d] somewhere.
I also made a rhythm game of sorts! Thought you would like it, it is a tower defense with rhythmic inputs. And I had to solve some technical issues and learn some stuff to actually keep the music sinced with the game logic, maybe that's why you kept the level short? If so, very smart move for a jam project!
Congratulations on the project!