You could be right, I don’t know. They could have developed simutaneously: as civilization grew the language developed and grew to cope with it, explain it, share it. The Stone Ages, after all, were a civilization of a type, albeit, prior to what we consider civilization. Consider the art in the Lascaux caves of France. It is communication of a sort by a stone age people who were developing, growing and found the need to express themselves. But they most likely lived together in some sort of civilization. When developed further, a hierarchy of sorts must have developed to push some folks into the peasant class you were referring to. Language certainly had to be part of it all somehow, whether oral or on the walls of caves.
