The introductory notes to the book of Judith in my Oxford Annotated Bible (NRSV) claim that the book is fictional. Is that true, and if so, why is it included in the Catholic canon if none of the books of the Protestant (non-Anglican) canon are fictional?
The book of Judith is a parable of sorts. If we were to throw out all the books of the Bible containing parables we would have to throw out the Gospels, too.
For more on this see How can the book of Judith be true…?