I like the presentation of this game a lot. You have great pixel art, music and the boss design is really cool!
I'm not sure I understand how the parry works however. I haven't been able to get the projectiles to spin. Sometimes I live through the parry, other times I still die when the character is curled up. I can see the projectiles change color when they get close and I'm trying to time it with that, but no luck.
I think I'd recommend giving the player some health because dying in one hit feels very punishing. For a jam ideally you want to balance your game on the easier side. I'd love to come back and try this game again though if I'm missing something!
Awesome job!