And if all the parts of the conversation are intentional, what purpose is to be served. There are countless ways for each conversation to be altered, similar to the game of Clue. If just one thing were said differently or one path chosen over another the outcome changes. Each person in the conversation has their own interpretation of what the other person is saying and the context in which it is taking place. Each person also has their own agenda whether it be intentional or subconscious.
Children learn to speak just by listening to others.
Children learn to speak without formal instruction. Soon they learn to say full sentences and create sentences of their own. With all the imperfections of our spoken language it is amazing how well children learn to speak. I am not saying language is not a perfect gift from God. I am saying that when we speak it, which is what children hear and imitate we speak our language imperfectly.