It is a fair question to ask, if you are claiming that the people are telling stories, how did they become such good story tellers?
I ask you this, from your memory of readings of the last century, can you not remember a description of a person as, he sure could spin a good yarn?
Of course you can. Depending upon your age you may remember a grandparent who could tell a great story. In my family it was my mother telling of being frightened of her grandmother's ghost stories. As a child I remember everyone, adults and children alike, sitting rapt while my grandfather told a story.
What has changed? Before mass media entertainment, people entertained themselves. For centuries storytelling was one of those entertainment skills.
Let me lay a little groundwork here before I am rejected out of hand. Working backwards we have cable, broadcast TV, radio and movies, live theater, traveling entertainers. At some point between live theater and "radio and movies" the art of self entertainment was lost.
This is nothing new if you are old enough to remember. It was a common discussion point hardly twenty years ago and if you find David Brinkley in the right mood he will talk about it today.
At one time people cultivated storytelling as a personal skill as much as they cultivate computer usage today. And anyone can be a storyteller if they just listen and learn from other storytellers. Save that today the breed of storyteller is few and far between. Being a good storyteller was a goal in life and something cultivated.
Let us take the people from Eastern Europe who tell stories of the Holocaust. The regions they came from were so primitive at the time that radio and movies were rare. They were old enough that they were raised knowing and learning storytelling.
And there really were internment camps and people in them. And there was a need for entertainment in them. If people entered them not knowing how to tell stories it was a great place to learn the art.
In fact one can imagine a favorite story theme being, "You think it is bad here, let me tell you about Treblinka." Obviously it would be a matter of making conditions elsewhere appear much worse than where they were. The best storyteller would be the one who could imagine the worst conditions elsewhere.
So we should not be surprised to find they were telling stories and in their tradition. Moreover we should not be surprised to find they were good at story telling. And finally we should not be surprised to find that we do not readily recognize it today.
We do not recognize it because we are not familiar with storytelling. We do not recognize that hitting the common themes is a sign of storytelling. And we have near zero examples of extemporanious storytelling these days save in bars limited to men where they are not expected to be true.
Contemporary research into the works of Homer find that the same storytelling style exists today in the backwater towns of Greece. First a playing to the audience and then on finding which story they want to hear, launching into almost exactly the stories of Homer or of the gods or whatever excites the audience. There is no qualitative difference in providing stories of atrocities. Prurient interests always excite the audience.
Thus we have the answer as to why they are such good storytellers and we do not recognize it. They grew up learning to be storytellers and we have to look back to our oldest memories to find examples of storytelling.
We are not equipped to discern storytelling from the truth. We are too far from storytelling. They were too good at it.