The art style feels like Undertale and Deltarune. Overall, you’re doing great I really enjoyed moving around.
The boss fight was difficult to aim at first, but after playing it about three times, it felt much easier. I think it would be great if, whenever the player reflects the ball, it automatically bounces back toward the boss.

I found the mechanic of heading the ball interesting, though I did find it a bit hard to get the timing right; I’d also say the soundtrack really complements the art style. I did run into a bug, though—the jester got stuck in the corner during the battle, and I got stuck too. Good stuff.