Bullfrogs and spiders are edible. Bullfrogs are hard to catch, but my NPC managed to kill many of them. Spiders fight back and are good at it, so you have to be careful.
Still, even with no resources other than those you collected in the shelter, it’s usually easy to grind up some early melee skill and run into a city to camp there. The scenario doesn’t warrant even half the point bonus it is worth.