Surplus value exists because labour power is a commodity.
And it is false to say that primitive societies "rejected" the commodity form; you cannot reject what has not been ever put up for your consideration.
Social relations are or are not reducible to money, depending on what society we are talking about; in a feudal (and consequently not exactly sane) society, for instance, social relations are not reducible to money (they are, perhaps, reducible to loyalty, which is a different organisational principle).
What is a "sane" society, anyway? Is there a pathology of societies? What absolute, transhistoric, principle is involved in classifying societies as sane or insane?
How does a society ackowledge an unredeemable symbolic debt?
And again, what is an irredeemable symbolic debt?
Luís Henrique