I think the brain needs something special to be able to understand language properly. Perhaps this is one of the things humans are particularly (well, extremely

I think the brain needs something special to be able to understand language properly. Perhaps this is one of the things humans are particularly (well, extremely) good at relative to our general intelligence. Many parrots can speak but it's not really language, it's more contextual. Same with the non-human apes that can "use sign language". Also your example is not good IMO because there are physiological constraints on animals' ability to speak similarly to humans, like needing a larynx