You'd have to go back to the Old Stone Age.
No. When Mandel's explaining the basis of primitive communism, I don't think he intends to imply it's desirable or possible to return to that past. (If he did, he'd be dead wrong.) Rather, it's necessary to go forward and create the basis for a new kind of communism - on the basis of abundance not scarcity.
Class society is based on a certain amount of scarcity too: that there isn't enough production for everybody to live a really decent life, just the ruling class. As the productivity of labor increases, modern communism becomes possible on the basis of supplying enough to meet everyone's needs.
Should be noted, BTW, that primitive society wasn't based on each individual producing only his/her own needs. Rather, most primitive tribes are highly communal. It's just the productivity of labor is so low the hunters and gatherers can only feed themselves/each other. There's no room for a ruling class living off other people's labor.
And no incentive to keep slaves, etc., since they wouldn't produce any extra after feeding themselves. Or not enough extra to be worth the trouble of guarding them.


