Thanks to past interventions, the economy is now rife with malinvestments and prices that don't reflect real demand. The solution is to allow deflation and other types of painful readjustment. Otherwise true growth will elude us.
There is productive consumption and there is non-productive consumption. In the Keynesian mind, it's not necessary to produce anything, so long as people spend and consume endlessly, even to the point of destroying real wealth.
Assuming that some groups of foragers indeed practiced "primitive communism," they would have died out because they had lost the fierce competition with the more economically viable "libertarian" tribes. Communism has never appeared spontaneously and "naturally" in the history of mankind.