Are stories like The Iliad, The Odyssey, and The Aeneid mostly myth/fiction, or is there a large portion of real historical context to the stories? What is myth, what is fictionalized, and what is historical? Or do we even know for sure?
Note: Similar questions to this have been asked here before, but for some reason most of the responses on these older posts have been deleted.
Or do we even know for sure?
There is the rub... we don't know much of anything about the works for sure. There have been a handful of archeological discoveries that have verified some things, for example we have found helmets that match descriptions found in the odyssey. And we have found some of the cities.
But beyond some small things like that we have nothing. We don't know if any of the named characters are based on any then living people. We don't know if the politics are in any way accurate. And we don't know if any of the events are in any way based on any real life events. So largely the works are treated as if they were mythical. They are useful to provide insight into the life and times of the people who were reciting the tales. They are not useful as history.
The Aeneid was written by Virgil but was commissioned by Caesar. Basically it was propaganda for Caesar Augustus to legitimize the bloodline of Caesar who "traced" his origins back to Aeneus and thus all the way back to Troy (which was considered Ancient and Legendary even then) and to Venus herself who was the mother of Aeneus. This certainly doesn't mean some events from the story couldn't have been borrowed from actual events, but it is very difficult to know.