Sorry, silver bullion was used as a currency in Mesopotamia 5000 years ago. Gold has been used as currency, both state-issued coins and bullion, for at least 2500 years.
I think the discussion is a bit different from what you pointed out. Bullion and gold both have physical forms which means they can be confiscated by a state (e.g, US Gold Reserve Act of 1933) or subject to strict import and export controls.
Bitcoin= no government, no control, no central authority to push around. it might not literally be the first digital currency but the first that is fully Autonomous. It's the first system of money that runs it's on its own.