You seem to be stuck in the (IMHO weird) idea of a user story being always something which is created by a business analyst making an interview with a user.
Sorry, but this is just a thought model, a simplistic example of how a user story might be created, but definitely not the only or the only correct possibility (probably not even the most frequent one).
A user story is just a sentence or phrase which describes a requirement from the perspective of an end user .
Who writes this sentence down is completely irrelevant. It could be an analyst, users by themselves, a developer, or any other kind of stakeholder. The person just has to "wear a user's hat" (but don't take that literally neithermetaphorically).
If the requirement is found by an interview, or during some brain storming session, if it is extracted from some existing documents, by analysing some UI of a competing product or completely invented by some ingenious person does not matter. Typically, it is a mixture of all these techniques.
This applies also for the different parts of the sentence.
So do yourself a favor and don't overthink this.