This is such a cool design! It's like a single-lane tower defense game combined with an auto-battler, that also has the feedback loop of an incremental game. What was your inspiration?!
I agree with Captain Melonlord's comment below - I think showing the player the stats of the different coins types would help make this more strategic. Currently, it's fun to watch the battles play out, but it feels a little like I am picking units at random.
I love that you are able to buy coins mid-battle. It builds great tension, where debt is approaching quickly, but you are trying to hold out to buy an expensive emerald or gold bar.
Congrats on the relase, and thanks so much for joining the jam! This is so impressive for a 13-year-old. The games I was making at 13 were not nearly this sophisticated, you have a lot to be proud of! I'm excited to see your future projects.