Did you know that Chinese didn’t have a word for “She” until about 100 years ago? In fact, Chinese operated without a female 3rd person pronoun for thousands of years, and it wasn’t a problem – until interaction with the west. Watch this video to learn the fascinating (albeit winding) history of Chinese gendered pronouns.
I agree with you that it’s a gradual process, but i think to say that it just appears spontaneously mystifies this process too much. Languages are spoken and shaped by people. They don’t exist in a magical void. Ergo, if a feature becomes adopted, it does so through social interaction and because of a series of choices by individuals. Once a new linguistic convention gains a critical mass of support, it catches on as the new norm. Nevertheless, every norm originates somewhere. That’s all i was trying to say. Not that everyone who adheres to these norms is making a conscious choice.
You are misunderstanding. We can talk about adopting linguistic conventions in terms of orthography and vocabulary for example, but let’s look at a practical example of completely unintentional change in grammar and phonology.
In Latin, there were 3 genders: masculine, feminine and neutral, marked at the ending of words. In the descendants of Latin, the same spontaneous changes that create different accents of the same language happened to make the neutral ending sound identical to the masculine one, and so they were merged.
There is no series of choices, no magical void.