Congrats on your first finished jam game! The strong points were definitely the enemy art and the general visual style.
I did manage to beat it, though it seemed like picking higher max stamina effectively was a downgrade that just made the stamina charge slower lol, when I didn't pick that it suddenly became easier. The timing/animation of the attack felt kind of awkward and hard to tell if it was doing what I wanted, could have used a little more feedback and responsiveness and maybe some more prominent animations and sfx. The combat itself was super basic and didn't seem to require either any strategy or much timing/reaction speed, so it really suffers from the individual attacks and taking damage not having any oomph to them.
Also the music was nice but without spooky ambient or active sound effects from the creepy monsters the audio experience doesn't quite fit the visual experience I think haha.
As for the palette theme, I don't have a problem with the graphics style as-is, but with 90% of the game being pure black or white which wasn't from the palette I don't think it really fit the theme very well. I think it would've been better to use the darkest and lightest colors from the palette instead of black and white for theme purposes. Outside the context of the jam though I don't mind the style!
Also a bit weird that you control the combat parts entirely with the mouse and the upgrade in-between entirely with the keyboard.
A lot to improve on but still a nice first go!