Congrats on making your first ever game jam. Since you asked for feedback, here's a couple notes :)
- A like the jump sound effect, it complements the pixel art style! It would have been nice to have a sound for when you take damage, too (I didn't realize I was taking damage at first)
- Nothing happened for me when I merged with the flub in the top right corner
- Maybe I took damage from the boss too quickly, but I couldn't beat it with just the starting attack (or I gave up after several seconds)
- I liked the changing weapon abilities with the colors!