That's where interaction comes in. Parents everywhere in the world go out of their way to inter-react with babies, or older people do. And they make it easier for babies to understand language. That's why we talk about interaction as being the basis of language acquisition. There are a couple of things.
Babies have to think that language is a good thing.
And the other is that they have to be given some clues about what's going on. Parents play an enormous role. I don't want to say just parents, because you don't have to be the biological parents of the baby, obviously. Plenty of babies are raised by other people and they learn language very well. But it does depend, not just on innate principals, which they may have, but it also depends on older people really getting in there and talking to them.