Humans introduce aliens to cosmetics, not all would go in their original place. -- Knitnan
Humans are well known to be attracted to shiny things. This eventually resulted in Humans making themselves shiny in order to attract mates. Jewellery is an almost universal concept, though not always universal in execution. Makeup, on the other hand, is not as universal as one might expect.
"So... you apply paint to your exterior to look more attractive?"
"Getting closer," said Human Jaz. "We call it 'war paint' because the ancient cosmetics were dual purpose. They were also used to decorate domiciles. And dye fabrics, now that I think about it."