We measure cognitive ability by our own cognitive abilities, which is our only measurement reference and therefore, construct a hierarchy with our cognitive abilities at the apex. Cognitive ability may include qualities which humans are unaware of.
Other species, such as chimpanzees, may be merely subjecting themselves to our 'training' in order to acquire skills with which to communicate with the human species and to eventually teach us their modes of communication and cognitive abilities, such as an English-speaking European living in Japan and learning Japanese culture/ language in order to communicate with those living in Japan.
Perhaps the chimpanzees realized that they were capable of leaning our modes of communication and that we did not have the ability to learn theirs. Just because Chimpanzee communication sounds like screeching to us, does not imply that it is a lesser form of communication.
What do our speech patterns and languages sound like to them?
The assumption that we are at the top of the scale of cognitive abilities is founded on a scale humans developed from observations made from a human p.o.v.
Cognitive abilities may be more extensive than we realize and we should approach the other species on this planet, not as lesser beings with lesser knowledge, rather as beings sharing this planet equally who may have alternate cognitive abilities than ours.
All species are unique in their own way. None are lesser or greater than any other.