It is important to note that the proposals for a supranational currency have been made with various, disparate goals. Some are primarily interested in some aspect of commodities, others primarily or completely the supranational-currency aspect. These can overlap in several ways. The primary possibilities:
Category: origins of money
How the euro illustrates an important point on the origins of “money”
This simple fact in no way contradicts chartalism nor credit-concepts of money. It augments them
Commodity exchange units-of-account almost certainly predate 3500 BC temple state-money. Neoclassical Econ is still nonsense.
It is not only perfectly possible for there to be a role for early exchange for understanding the origins of currency systems. It is almost surely necessary.