Congrats on this being your first game ever. Finishing and submitting something to a jam is a huge step by itself.
I liked the core idea of digging down into the caverns and selling what you find. There's something naturally satisfying about that loop; mine resources, go back up, sell, upgrade, repeat. Buying the torch to see deeper underground was a good addition, as well. It adds a bit of progression and makes you want to push down further.
If you keep building on this idea, adding some sound effects would go a long way in making digging and selling feel more impactful. Even simple SFX can really boost the sense of feedback.
For a first game, this is a solid start. You've got the foundation of a progression loop here.