Human language is slightly more complex than that.
First you have to analyze the languages that existed before human language. And I am speaking of language using vowels and consonants.
That’s the very nature of human language: first articulation vowels and consonants; second articulation morphological architecture; third articulation syntactic architecture.
Body language and facial language take part in communication but are NOT part of human language though intonation is and can even be part of the first articulation with intonation and tones.
Human language is used in the wider communicational situation that has its own syntax that has been transposed or translated into the linguistic syntax of this or that language.
Speaker — Message — receiver becomes linguistic when it becomes Feeder — Feed — feedEE — Food or Eater — Eat — EatenItem.
I have worked on the calls of monkeys as recorded in full nature, otherwise it is no longer natural, it becomes humanized. And they do not even reach the first articulation since their vowels and consonants are not even rotated and with six or seven sounds their only produce five or six calls and when two calls are used together the meaning of the association is holographic like each element associated and it has no real relation with the associated elements.
We can only get to valid hypotheses if we look at the concrete natural communication of animals, including the human animal, in their NATURAL habitat.