Hey! The game is not that bad, you got all the basics things here is some suggestions to improve the game :
- Add different level and a bar to see how much hp the boss have
- Differents shoot pattern for the boss (difficult at the start but easy when you understand that it's always the same)
-Maybe a short story like one text when you start the game : "Oh no you steal my cookies I'm gonna fight you" it's nothing, but can make the game very funny and cool!
For a first gamejam it's pretty good (at least your project is finished and playable), keep going, one day you will make insane games!