Wild chimpanzees alter the meaning of single calls when embedding them into diverse call combinations, mirroring linguistic operations in human language. Human language, however, allows an infinite generation of meaning by combining phonemes into words and words into sentences. This contrasts with the very few meaningful combinations reported in animals, leaving the mystery of human language evolution unresolved.
At this point I feel like chimp communication is protolinguistic - it’s not language yet, but it’s really above non-linguistic communication.
The main difference I see is the lack of anything resembling a tree structure. Human sentences typically have one word working as the “head”, words connected to that head, words connected to the words connected to that head, and so goes on; at least in theory you can extend it to the infinite. Chimp compounds however seem to be either headless or at least not allow branching, and they definitely don’t allow any sort of nesting.