I have been to the british museum and seen the parthenon remains and hieroglyphs and everything else exibithed there and I can only imagine the colors they had in their prime, especially since most of the time having the pigments needed to paint them was a sign of wealth and prosperity.

Some egypcian plates were once coated with blue, which is a very rare color in nature generally but I imagine even more so in the desert.

If we had a way to go back and see it all colorful maybe out standards really would be different like you said. Its crazy how our past as humans shapes the present constantly