Disclaimer: I fully understand this is a game jam game not everything can be done but even then I give very "tough" feedback so if you can't handle that kind of "criticism" it's ok just don't read my message.
I atleast myself don't really see the theme application, it might be the story but it's a little bit of a stretch if you were to ask me.
It would be nice to have a counter either in UI or above player of how many "ammunition" they currently have as it is kind of hard to tell (at first glance for me atleast) how much I have left... also more clear feedback when you have no "ammunition" and also when you have "full" too as I see you can only have so much.
Slight Edit: It took me a second attempt to realize this is already a thing but it is still kind of hard to tell so I'd suggest sound effects too for when you have full and no ammunition at the very least.
The UI right now seems quite big, not that is a problem right now but it could be in the future if you were to add more UI elements (and also obviously continue working on the game) so I'd say just be careful with that.
The character sprite pops a little too much atleast in my opinion in the sense of it feels like a different style compared to most of the rest of the assets, remember, consistency is key.
It's unfortunate about the "You Win!" screen but that's the only bug I found and atleast you are aware of it so only thing I'll do with this one is suggest which I suggest you could add either highscore of coins alongside the coins of "this run", enemies defeated, it all depends on the focus of this screen and the game's goal obviously so do what you must.
These types of games benefit a lot from enemy variety, 2 enemies is already more than most but I'd say around 5 is the "sweet spot" in my opinion
All in all. Pretty fun and I like the concept, good job.