Wow, this really is incredibly good looking for how long you had to work on it, great job there.
Honestly my main criticism is that you're maybe trying to do too much within the single button scope. I could see this being the start of a really neat little fighting game, but without the ability to properly move and dodge without relying on the jump attack, it feels a bit unresponsive, which again is totally understandable given the constraints.
Amazing work!