Supposing there are Aliens FWIW I don’t know that they would perceive the same visible spectrum that we do, which might effect their ability to differentiate by color. And they might not even perceive colors at all perhaps focusing on patterns or perhaps use some sort acoustical sonar system of high pitched shrieks or an electrocapacitive perception captured by elongated dactyltennae hands with which they can sense the world around them.

No, I am saying that skin tone would not be as important a feature.

For example, lining up those dead bodies by skin tone alone would have Central Africans mixed in with South Americans, Austronesians, and South Asians, Northern Europeans mixed in with East Asians and Inuit, Southern Europeans mixed in with Indians,Central Asians, Native Americans, and Arabs, etc etc.

> Aliens may as well sort us by the colour of our pants as soon as the colour of our skin

This made me chuckle. But it is a good example. I bet there is a lot we can infer from people based on their common go-to colors for clothing.

That depends on the Alien's primary mode of sense. Which may not be sight. Sight is particularly strong for humans. But what if the Aliens primarily distinguish based on smell like many animal species with poor colour vision?