As so many others already mentioned, the art is incredible!!!
I just wish your art would be animated to make it even more alive (they already have faces etc.) but I know that would be insane amount of work for a jam and as far I see this was even an solo entry hence no time for that for sure.
I am not a card game player so I cannot give feedback for improving the gameplay, but I enjoyed playing it. I guess my main motivation to proceed was seeing more art from you.
Maybe as a tip for future, look out for a 2d developer with some experience in jams and team up with him. I guess you could unleash more potential in a jam if you spent the whole week on art. I can imagine that would end up being insane.
Great job on this and looking forward to see more from you!