Okay, so, I can tell that this is probably one of your first jams/games overall, so I won't be too harsh. The game works overall, and it still takes lots of effort, especially when you're only starting your journey. But I'll quickly get over everything I think - this will help you turn this into something much more cool, after all!
1. Let's adress an elephant in the room. the game really needs sound, it makes up like half the immersion, you can't go around it, sfx can easily be found on platforms like freesound.org
2. There isn't much art here (which is fine) and by the way these assets work together, I'm guessing that those are bought/downloaded assets (which is fine, and sorry if that assumption was wrong), and the thing that I don't really like on the graphics part is lack of consistency. Your main character has an outline - and it only makes sense if your skeletons also have outlines of the same color, you don't need to be good at drawing pixel art for this, heck, you can do it in one click in aseprite. but it will add that feeling of whole game instead of a bunch of assets together (also, the rules there aren't that rigid, but they must have logic behind. so, your characters could have outline, but not your environment, which makes even more sense because originally outlines appeared to distinguish characters from environment).
3. There needs to be more.. game. like ok, this is just a game where you can move, you can attack, and skeletons can attack, and there isn't much beyond that. But just to give a kind of direction, I'll say what I actually feel about combat right now. It reminds me a bit of dark souls, where when you're fighting groups of enemies, you don't just attack enemies all you can, but rather wait for timing when you can attack and not get hit in return, and think about your positioning. maybe you should bring it into that kinda direction? add more movement options, like a quickstep back, maybe a roll if you're into the dark souls idea, a block, a jump (like not a high one, but as a way to dodge attacks that aim at legs), more stuff regarding the way enemies work and it will be more interesting to play.
And yeah, make the hearts work lol, like they work, but not visually