Gold has a lot of practical applications now (although is of course still treated as a ‘precious’ metal of value), but hundreds of years ago it was just a shiny metal. Why did it demand value, because of it’s rarity? Why not copper, because it was too easily found? What made it valuable ahead of other similar metals?
It looks good. Every culture that’s found gold has made jewellery out of it. The rest follows from there.
It doesn’t tarnish, so once you’ve already decided it looks good, you then notice it doesn’t age or spoil like pretty much everything else. That gives it a magical aura and allure.
It’s fungible (consistent and exchangeable)… gold here looks exactly the same as gold there
It’s malleable - can be easier subdivided into units for exchange. Can readily be worked into attractive decoration.
Although it’s rare this isn’t what drove is attractiveness (the Inca had abundant gold and still chose it to make jewellery out of, it just looks better, even if there’s a lot of it), but scarcity did help it become a reliable store of value across the middle east, africa, asia and europe.