Hello tab3ri, great game! And congrats on your first jam entry!
I have a couple of suggestions and comments for you if you're interested. I'll try to avoid things that have already been stated in the comments.
What you did well:
Your art style is great. It's cute and simplistic, and the enemies are distinct enough to where you can instantly identify how they work.
The enemy composition is done good. You have a fast but low health enemy, slower enemies but more tanky, and then a very high health enemy but with a bigger size and very slow speed.
The level changes are good. Your bullets changing in fire rate and damage between the 3 waves makes the gameplay more dynamic. I really loved the purple bullets.
Suggestions:
I think an enemy that moves a bit diagonally could make the game more fun.
Early hooks are important. One example is a wave progress bar or some sort of indicator. Until wave 1 ended I thought there was nothing else to the game.
The ocean sounds in the background are nice but music would be a great addition.
Overall, great job. If you intend to keep participating in game jams I wish you the best of luck!