Earlier quoted context omitted.
If it was that straightforward, we’d already have bots that pass the Turing Test. Whatever natural language is, it’s not an API. Might have some overlap, but it’s different.
Nobody said it's easy to implement :) I'm curious - what differences do you have in mind?
To simplify that and put it in more technical terms, an API is perscriptive and a language is descriptive.
If a bunch of coders decide to start capitalizing "Class" their code won't compile. If enough people start using the word "aint" it becomes a word, regardless of what the dictionary says (see "irregardless"). There is no single authority that can decide what is and isn't a canonical definition.
This is why spoken languages evolve so much. Even languages where we've explicitly tried to go the opposite direction (like Esperanto) have evolved into multiple dialects, where subsets of the community simply ignore the standards and still communicate with each other just fine.
Note that this is the opposite of what you want with a federated, universal API. The whole point of an API is to standardize between unfamiliar devices. Language is actually pretty bad at standardizing communication between unfamiliar people. Even in the US, different regions and communities use different euphemisms, terms, and definitions.