I really like the randomness and roguelike elements in this. The game feels satisfying to play. For this jam, I think it’s great overall. I do think the items could be incorporated into the game's theme a bit better. Other than that, the game is easy to understand and includes most of the required items.
If you plan to continue working on this after the jam, I think it would be great to add more things happening during mining—like hazards to avoid or interactive elements such as mushrooms or animals that could affect your mining. It could also be more interesting if you didn’t just buy upgrades, but had to find them in the cave and bring them back safely. These items could have an ancient technology or artifact style to better fit the game’s theme.
I really like this game and would be excited to play more if you decide to keep developing it!