Yeah, that’s the part I have trouble with. Leaves are green, the sky is blue. They are very different colours. It’s not ambiguous like whether teal or turquoise is green or blue (I could easily see either of those being labelled as either blue or green), or different shades of the same colour like fuscia or maroon. They are different primary colours of light.

It’s just weird to me that two very common every day colours that don’t look anything alike wouldn’t get distinct names. I understand that the blue photoreceptors we have are the newest ones and are less sensitive than the red and green ones, but I wouldn’t have figured that our evolution of it to the point where we see what we currently see (if you aren’t colour blind) would have been that recent. I expected hundreds of thousands of years, not tens of thousands or just thousands, which is what it would need to be to explain cultures that didn’t differentiate between the two until recently.