That's great, it has a lot of potential. In my opinion you should make clear those stats from the start, just by saying what will happen if you get hit cause otherwise it feels like nothing is happening.
I would add visual feedback when you're damaging the enemy, like a flash effect and maybe some small screen shake. At first I didn't understand what the shield bar was, I thought it was the player's, so maybe the enemy bars should be at the bottom of the screen, I think the top right is usually player HUD. I'm not a game expert and it's just my opinion but I hope my feedback helps!