Hey! First off really cool demo and solid foundation for a game! As, a solo dev myself, I can understand how hard it is to create something like this :)
Here's my feedback:
1. The jump feels a bit too weighty imo; it feels like the character is wayyy too heavy, especially compared to what it looks like. It's almost as though we are jumping from a pool of slime or something.
2. The keyboard controls are fine, but I think using the arrow keys to control the camera is a bit weird(It's kinda hard to reach as well, as there are no other keys used in that region of the keyboard). Maybe consider changing it to WASD as well? Should be more intuitive :D
3. The enemy attack tracking is a bit too strong I think. This is a bit suggestive, so I recommend that you take feedback from other players as well, but I think that enemies being able to flip around mid-attack is BS. Like you could have dodge through the attack in time, but then the enemy just flips around and hits you either way.
Keeping all my criticisms aside, I think you also have a great atmosphere and artstyle going on! Good job! :D
Anyways, keep in mind that all my feedback is suggestive and that you may choose to address or disregard them as you will based on what kind of game you are trying to make.
Good luck for continued development!