We may be quibbling over definitions. But do you believe that no mammal has an instinctual understanding of using nipples? Or that humans are unique among mammals in that regard?
I'm afraid I have no idea about the answer to either of your questions. I assumed the "we" in your original post meant "we humans".
I do understand that humans don't have an instinctual understanding of using nipples, human babies have a physical sucking reflex that kicks in when you put anything near their mouths. They usually quickly learn that sucking a nipple in a particular way gives out lots of yummy milk.
