I think just a few more mechanics could turn this into a full game. Attacking an enemy is a good start, but after you kill the enemy maybe you could introduce another enemy to fight. But before you fight the new enemy you could upgrade your character based on how fast you killed the previous enemy. Or you could introduce a bigger map so that movement has a bigger impact on the game because you'll have more of an opportunity to evade attacks and fight back from different positions. Either way, it's a start to something that can be grown upon. Try expanding it after the jam ends!