Thanks for giving it a play. I wasted many college nights playing tower defense flash games.
So the wild man enemy only targets the cart, you will seem him pause when its destroyed or makes it to the drop off. The AI works off an array of tags, it prioritizes the closest target. That enemy only has the cart as an option. One thought was enhancing this to add priority list, so maybe the good guys rush to help the cart when it is attacked.
Balancing difficulty is always a challenging piece in these short Jams.