And when classical art used any thing like giants, sorcerers or cyclops, it was always about canonical depiction. Listeners knew that fair folk is X and they do Y.
This is not the case. Hesiod and Homer disagree on almost every single point about the Cyclops, for instance. In Hesiod, they are children of Gaia and Uranus, brothers to the Titans, older than the Olympians, smiths, and confined to Tartarus. In Homer, they are Poseidon's children, shepherds, and live on an island. If you look at Catherine Briggs's
An Encyclopedia of Fairies you will find that English accounts of what fairies are like and what they are likely to do vary widely from region to region. These discrepancies are not surprising, since travel was difficult, most of these stories were transmitted only by word of mouth for a long time, and even when they were written down, few people could read and even fewer could afford many books.
In the case of folk tales, the notion that fantastic creatures are there for the sake of the plot just doesn't make sense, for many folk tales don't have plots. Two typical tales from Briggs:
>A workman on his way home in the evening finds a broken doll in the road by a stone and hears passionate weeping coming from under the stone. He sits down in the road and fixes the doll, lays it by the stone, calls "There you go, girl, I fixed it for you," and goes his way. The next day the doll is gone. He has good luck after that.<
>A farmer going home late is chased by an enormous black dog. It is almost on him when he leaps across a brook, and then it stands baying on the far bank, unable to cross the running water.<
There are many correct ways to read any story, so that it is impossible to say what the one true function of any part of a story is, but I certainly find it plausible to suppose that people who saw almost no strangers in the course of their daily lives would be concerned about the kind of people you might meet in the woods, on the roads, or in the evening. Any stranger would seem uncanny.
You can read Polyphemos as a thing that happens so that other things can happen, but he isn't always read that way. It has been pointed out that Polyphemos breaks hospitality laws in every possible way, but it has also been pointed out that Odysseus and his men also break hospitality laws by walking into his home and helping themselves to his food. They act like animals, expect to be treated like guests, and instead are treated like animals. This eventually brings Poseidon's curse upon them. Read this way, the episode looks like it is about how to behave toward strangers when in their land.
I'm just not going to argue about whether QC gives the depth of detail and resolution of character of a comparable short novel or short story. It would be like arguing about whether a patch of blue is a patch of red.
Arguments having been dutifully made, full disclosure.
All my talents, such as they are, lie in the humanities, and after years of careful reading in the humanities, I am sometimes thoroughly sick of humans. It is pleasant to imagine the company of some other sort of rational creature.