Gold never really served as a currency, rather as collateral. If gold is a currency than any marketable asset is. A good definition of "currency" or "money" would be one that distinguishes its characteristics from commodities and the only useful one I know of is the "credit theory of money". Money is a promissory note, an accounting device and that is true for at least 5000 years of monetary history tracking it back all the way to ancient babylonia. Throughout that history money has taken many forms reaching from clay tablets, metal coins, tally sticks, paper money all the way to digital currency but all those share a common principle which is that they are all records of indebtness, promises to pay. Barter is not and has never been the default mode of commerce at all or a anthropologist Caroline Humphrey put it:

“no example of a barter economy, pure and simple, has ever been described… all available ethnography suggests there has never been such a thing”.

Barter as a form of commerce pre-dating monetary economies is a myth, a post-hoc rationalization of how money might have came about from the perspective of somebody that already lives in a monetary economy and it's entirely an armchair theory that does not rest on any historical and anthropological evidence.

What is true is that between parties that do not have an established relationship barter occurred and it is true that people seek to hold assets and demand tradable collateral during periods of unrest. But barter has never been a primary way to do commerce between parties that had a long-standing relationship. A theory of credit-money is way more useful to explain real world behavor than a metalist approach is. Gold isn't used in daily transactions, it primarily sits in basements and is also is not an input to allmost all of production. What makes us rich in real terms is not gold but knowledge, machines and technology.