A little complex for a jam game, I would like to be able to play your game quickly. Otherwise, I like the music.
I don't see any reason to defend any row except the one with your castle. Also, the AI doesn't attack my castle, and seems to just pick a random row.
This might have been better if it was turn based.
Some visual polish would be nice, walking animations for the soldiers, change the default godot buttons, etc.