Why is that fair to assume? "Books" were extremely rare then. Some random librarian had to include those books, and likely leaned towards taking all written works due to scarcity.

Likely some other librarian disagreed with the inclusion and many readers disagreed with the content. They must have had a system for all of this. It was clearly far less open than Wikipedia.

IIRC, they took books from all ships in the port, in many languages. They likely had many "errors" according to other librarians and many readers.