> couldn’t have become currency under the definition you’ve presented here.

gold and silver were bad currencies back then, when people had no real alternative. People clipped coins, and debase the currency. People horded them when times were tough, and prevented lending and circulation, causing issues with the economy regarding liquidity.

Have a read of https://en.wikipedia.org/wiki/John_Law_(economist)#Economic_... and educate yourself about the past.