There are humans who can communicate somewhat effectively with chimpanzees using sign language, does that mean humans now have access to the several hundred yea

There are humans who can communicate somewhat effectively with chimpanzees using sign language, does that mean humans now have access to the several hundred year old chimp culture? I don’t think so. Anyway, while we can assume that whales and dolphins have exhibited advanced behaviors throughout the time their species existed do we have any evidence that these behaviors did not develop independently in different populations and were lost or recreated again over those millions of years?