How do young humans acquire the language of their parents/friends/elder peers etc? It’s a mystery, but it inevitably happens in 99 percent of healthy cases.
If language appears naturally in the brain, then you’d expect to see children formulating their own private languages. But, the very idea of a private language that only you know and understand is silly, no one would understand you, you simply have to acquire the language of your parents and your elder people.
That goes to say, language cannot possibly occur naturally in the human brain. It MUST be acquired.
I have three small nephews. They’re very dear to me, and I’ve been lucky enough to see all three of them grow up from infancy. I’ve seen them grow bigger, and also I’ve seen them acquire language, at this stage two of them can speak proper English sentences, the youngest one is just at the cusp of being able to speak like his older brother and cousin.
The first things they spoke to me were things like this, “Uncle, me, go , here, sticky”. Which I took as meaning, “Uncle, this area over here is sticky, some jam was spilled.” (some jam indeed had been spilled)
What I gathered from this was that words in themselves seem to be innate in humans. They knew the words they needed to convey their idea, but they simply lacked the syntax and grammar to express their ideas in a way that everybody else would understand perfectly.
Words (feelings/thoughts) are innate to all humans, but it takes a few years for young humans to grasp the concept of arranging those words in a proper way as to make them understandable to all other English-speaking people.
Anyway, I’ve said nothing here, but language is a funny thing, huh?