I can't know why others would give low ratings to art and music, but what i would think:
1. the pixel art scaling is different on the characters and weapons vs ui and backgrounds- not a huge deal to me but others might care more.
2. more importantly the background sometimes lacks contrast with the characters on screen making them hard to pick out
3. the music is balanced a little loud but i liked it. i think it's good. maybe some people would rate it lower though. one problem may be, despite the song being good, maybe it doesn't fit the atmosphere you were trying to create.
I think the bigger issue is the lack of satisfying sound effects/shader effects when you hit an enemy or get hit. Having enemies flash, get stunned or shake, ect. would go a long way for visuals. For sound effects, make more of them and make sure they feel impactful. That's really hard to do though, I'm still not good at it but I try my best. I like calling this sort of thing "the juice".
basically, add more juice and you'll get better user feedback.



