Those other things are some of the potentials of engineering, not things we need to do right now. You are asking us to think big for the experimentation phase, after all
engineering from a suitably good roll for walls will give us a strong base to grow from.
Division of labour re: keeping people safe when gathering, doesn’t require bows, as we presently have spears and bolas to keep people safe. Recent deaths were as a result of trying to tame lions, and I don’t think they would have been prevented if we had bows. Equally so, if the bows don’t fix the enemy problem, we have just as much risk and no real extra ability to keep ourselves safe.
Taking at least the former into account, bows wouldn’t necessarily reduce the risk to those of us gathering food (and other resources) so the flow of resources is still at risk regardless.
Walls would protect those that aren’t out getting resources, like the very young or old, sick and injured, so those out gathering actually have a place to come back to, and it would also allow resources like people and weapons which might otherwise be used to protect the people back home to be used to protect the people out gathering the things keeping us alive.
