Gold has been valuable for centuries. There is no BitGold network that, if it went under, would cause your gold to simply evaporate. Once mined and processed, gold is incredibly stable, 2000 year old gold coins can be dug up and sold as antiques.

All currencies have value, not because "humans" value them, but because some organization of humans said "this piece of paper is legal tender". They lose their value when that political organization falters. What political organization is behind bitcoin etc.

Beaver pelts stopped being useful as a "currency" when there was no ready market for furs, it was never a currency, it was a fungible asset.