Probably their brains are too small. What we find most interesting is the overlap. Some chimps lack even probe technology, and are no better at catching termites than baboons are. There are human cultures barely up to the highest chimpanzee standards of termite catching, and others only on a par with the baboons. No sharp boundaries are apparent here separating baboons from chimps, or chimps from humans.
Chimps also drop branches on intruders and sop up drinking water with leaves.
While they cannot be described as fastidious or obsessively hygienic, chimps are known to use leaves as toilet paper and handkerchiefs, and twigs as toothbrushes. When successful, they often manage to open the lock. Like us, they can sometimes use their intelligence to escape from bondage. Male chimps like to throw missiles-whatever is handy, generally sticks and stones. Females are much less interested in missiles.