You may have knowledge of Donald Duck but can Donald Duck give you knowledge and wisdom? Answer: no, therefore Donald Duck has no objective existence he is just a cartoon character.willieHindu
Even imaginary beings can impart knowledge and wisdom. For many children in the early days of television, the cartoons provided many of their moral and social skills. As well as an introduction to classical music. Please note that the script writers were anonymous at least as far as the kids are concerned. It was the characters that provided the message. Don't bother with a rant about the bad messages, although discussion of the messages would be welcome, the beauty of fictional wisdom is that one can choose that which seems wise and reject the garbage.
I prefer to get my history from fiction rather than from the biased "historians." A successful fiction writer will be in tune with the ethos of herm time or hesh will not not sell. I suspect mining wisdom from the remainder shelves is about as useful as mining it from the history shelves. One must account for the bias evident in the story, a good story is inevitably biased, but given the bias the wisdom supporting the bias is useful data. Incidentally the perceived bias of the author is irrelevant. Creators are telling stories to the culture which will sell. If their own dysfunctional bias becomes too prominent the story will not sell.
Humans are story learning creatures, and whether the story has an identifiable author or is simply part of the culture it is always a good story, with unequivocal morals. Also note that stories can take many forms, verbal are the most common including those using music as a mnemonic, but some art and recently visual stories are threatening to become the dominant story telling form. Visual stories are not new it is just that technology has made them easier to produce and distribute.
There are two additional fictional sources of wisdom: Fable and Scripture. Both are specifically collections of folk or tribal wisdom, frequently by identifiable authors who happen to be great story tellers. Most of the Pentateuch stories that everybody can recite from memory and frequently used as lessons are from the Yahwist. The main difference between fable and scripture is that one is expected to find and learn the wisdom from fable while scripture is generally expected to be taken whole as wisdom. In some religions scripture is TRUTH™ and for a particular translation every word is accepted as reflecting the will of God. "God" capitalized is universally used as the god created by Abram or possibly his tribe and adopted under many names or symbols by the many religions and sects and cults that accept Abram as the founding patriarch.
If one treats scripture as fable that is some wisdom and some garbage it becomes a valuable source of wisdom about our friends and adversaries that are believers.