Just a thought.

Why is cow's milk the cultural norm for milk? Why does every sort of milk get a specifying prefix- goat's milk, breastmilk, etc.? Humanity is the cultural default for food- we don't say "people food" for the food that adult humans consume. It's also the cultural norm for clothing, hair, grooming products, etc. So why isn't human milk just milk, and the milk of other species must be specified?