What is currency? Non edible object used in exchange for goods or services (as paper, coin, etc).
If I trade you a 1 ounce gold ring for, say, a cow, I just bought the cow with gold. It wouldn't matter if the gold was in the form of a flat disk with Caesar's inscription on it or if it was in the form of a size 3 wedding ring with no diamond from Zale's.
I think your attempting to discount the use of gold, silver, precious metals, etc in the old testament as money is far fetched and stretching things.
In
Deuteronomy 14 I believe it says people who could not carry oxen, sheep, produce etc to Jerusalem were to sell the products for MONEY and then upon arrival in Jerusalem they were to use the MONEY to BUY oxen, produce, wine, etc and pay their tithe WITH THAT (by eating it, in fact, along with Levites, strangers, widows, and orphans).
So the apparent claim that money in Genesis or the OT in general is irrelevant is, well, irrelevant. Things were used as currency, that is, non edible items were used as a medium of exchange for edible foodstuffs.
Gold has been money since the beginning of recorded history. Everyone outside the CNN crowd knows that.
