IIRC correctly gold has been a popular currency because it has properties that allow it to fulfill the functions of a currency quite easily - it's uniform size and weight and overall geographic availability lend nicely to being a unit of account, while its natural scarcity lends itself to being a store of value, and its durability lends itself to both its unit of account and store of value functions.

It's also worth noting that the volatility of gold production has historically played against its function as a store of value, as fluctuations in its price have had impacts on the larger economy.

All of this is to say that the only reason gold has extrinsic value as money - why so many societies have seen it as money - is because it has natural properties that map reasonably well into the needed functions of a currency. It's not unique among natural currencies, rather just a first among equals.