Yes! Definitely need to rebalance the whole thing. It was kind of a last minute realization for me too while I was testing it with friends. And as you said, the feeling is a bit forced because of the lack of UI, something I knew I needed to do, but was scoped out for since it was so close to the deadline. (I'm not great at pixel art, and this was actually also one of the first times I've done it myself)
I think the idea of having stats is interesting and I could see how it would work. So definitely not a bad idea! I think the game would need to be a lot bigger, though, for that to work. If I made another card battler, that's something for me to keep in mind because I can see how intriguing it is.