Very cool idea, and nice job on implementing all these different items. I can see the RoR inspiration.
However, I feel like some of the time you spent on these could have been better spent on properly introducing the mechanics of the game. I'm guilty of the same, on my first jam we were so infatuated by the gameplay that we forgot to put any menu or tutorial. So nobody played our game :(
Once I read the description I had a bit of fun !
Still, it felt a little pointless. Some kind of progression system, like a boss or more varied enemies, would've been nice. Without points of interest or anything to show that I'm advancing in the game, I didn't really feel like anything was happening. Waves are coming, but that's it. I also didn't understand that the items were upgrades until I read the description.
I hope I don't sound too harsh, I think you've got a nice start that can be expanded upon ! Being able to unlock more and more wagon, and the cahotic fun of having to manage all their cooldowns, is a nice starting point for a fun game. I also like a lot what you're trying to do and your ambitions for this jam