> where a bunch of deaf children in a an environment without much adult interaction did manage to create their own sign language
You probably had Nicaraguan Sign Language [1] in mind. I think it’s a good example of the human brain’s ability to invent something and acquire knowledge easily. What I tried to show with my comment is that when human intelligence is discussed, it’s easy to refer to all instances of human achievements around us, but they are essentially accumulated cultural knowledge. Because of this, we tend to overestimate our intelligence, at least when comparing an individual human with an individual primate of another kind.
So, it’s also interesting why humans are probably unique in this ability to pass on and accumulate information, while other apes (and crows) limit this to skills like retrieving ants with sticks and breaking shells with stones.