While you might be correct that the first taxes were non-monetary, they were imposed upon subjects of the ruler/king. Not on an equal sovereign. I think to this day that is still true. Exercising sovereignty is the challenge us Americans currently have before us.
Additionally from my research, historically, money has been gold and silver coin. In recent history the practice of fiat paper currency has been to loan it into existence, at interest I might add. Also note that when gold and silver are used as a country's money, there is minimal inflation and more often than not, deflation. That deflation helps the general population rise in their standard of living.
Thanks for your comments.