Thanks for that link - that was a very interesting and well done show on the possible history of a real life King Arthur. Cool stuff.
Your storytelling approach is pretty interesting, and actually relates to the Arthur legends. There was probably no actual, one-the-only, "real" King Arthur. Post-Roman kingdoms are however historical, and there must have been leaders. And each kingdom was probably in a continual struggle with each of its neighbors, gradually getting subsumed into one another, much as England grew out of the Heptarchy (seven kingdoms, plus a bunch of decent-sized other kingdoms with unfamiliar names that didn't make that particular list) and was nailed together well before 1066.
The legendary version of Arthur and his knights shares characteristics of Robin Hood and his Merry Men -- another group for whom there is zero evidence that there ever was such a single, actual, one-the-only person and followers. This is a storytelling practice, and isn't meant to convey history, rather, it's there to, well, entertain the listeners and among young listeners, mentor them.
This differs from historical people such as George Washington -- yet some stories got attached to The General. He crossed the Delaware, but he didn't throw a dollar across it (number one, there were no dollars yet; number two, the actual story as related by his step-grandson is that George in his youth threw a small piece of slate across the Rappahannock). The cherry tree anecdote was apparently invented -- or borrowed -- by a later biographer. That doesn't mean that Washington didn't exist, of course, even his remains are still around and in a marked sarcophagus.
Vortigern, often shown as a villain in the Arthurian legends, was badmouthed in some "Dark Ages" sources as well, but he was a real person. Some of the stories about him are stone cold nuts though, so, V is more like GW.