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 some inclusions and certainly many readers disagreed with the content. They must have had a system for all of this. It was far less open than Wikipedia.

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