Well, yes, we kinda do: there are no conscious humans without any ability to learn?
When you have severe memory impairments, those usually affect your long-term memory. Your ultra-short term (working) memory being absent renders you unconscious.
Even if what you said were true, we do not know that humans are the only case for consciousness.
Even if what you said were true, we do not know that humans are the only case for consciousness.