back then nomads /humans who moved from place to place they created a stable food supply like getting fish from rivers,growing crops. and also they were gathering, hunting. so they had enough food to maintane them and there love ones. and
And after nomads started to be able to get more food and eventually started getting surplus/leftover's they said that they were gonna stay there because it was a not bad place and had enough food to survive. they started gathering like stone,wood and clay and began making permanent shelter.
After they were done building thier shelter their population in that area started growing they started asighningn jobs and soon after they had no more job's for other's that they started to share jobs