One possible origin could be from the misinformation or exaggeration of some rare and already disturbing historical events. Maybe there were some cases of violence or extreme behavior in the past that got distorted over time into this very extreme story. Another factor could be the human tendency to create horror stories for entertainment or to pass on warnings in a very extreme way. For example, it could be a cautionary tale that has been blown out of proportion. Also, cultural differences and misunderstandings between different groups in the past might have contributed to the creation of such a story.
The origin could be related to the human psyche's need for extreme and sensational stories. In some cultures, there are tales of monsters and inhumane acts that serve to define the boundaries of what is acceptable behavior. This story might be an extreme version of that. It could also be that in the early days of exploration, when different cultures first interacted, there were misunderstandings and rumors that got passed around. For instance, a cultural practice that was misinterpreted as cannibalism could have been the starting point for this kind of story. Additionally, the oral tradition of passing on stories from one generation to another might have led to the evolution of this particularly gruesome story as details got added or changed over time.
Chapter 517, "Master Jiang Opens the Third Eye Online", is the clearest early answer because it turns Bai Lu's situation into a concrete plot event. It opens with Mu Ye was completely caught off guard and stood there dumbfounded for...
Chapter 676, "Third Uncle Will Buy It for You!", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter turns that into something concrete by moving from Jiang Zhao Yuan felt somewhat embarrassed by such a direct revelation.
Chapter 684, "It doesn't matter if it gets broken, I have the money to fix it.", is the clearest early answer because it turns Jiang Yan's situation into a concrete plot event. The chapter gives readers a real answer by opening on But Jiang Li had already evolved;
Chapter 601, "Going Home", is the clearest early answer because it turns Ling Bei's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Gu Qiang was in a very pleasant mood.
Chapter 759, "You Should Hurry and Check on Your Brother", is the clearest early answer because it turns Miss Jiang's situation into a concrete plot event. The chapter turns that into something concrete by moving from Everyone in the circle knew that Old Sir Jiang's belief in...
Chapter 543, "Please Name Ten Things You Dislike About Su Yinwan", is the clearest early answer because it turns Su Yinwan's situation into a concrete plot event. It opens with What did Jiang Li just say? and closes on No, how dare this guy try to seduce Jiang Li?.
Chapter 621, "What Makes You Think I Would Save You?", is the clearest early answer because it turns Sister Li's situation into a concrete plot event. The chapter turns that into something concrete by moving from The two walked for a long time before they reached a point where the...
Chapter 577, "Cat and Mouse Game", is the clearest early answer because it turns Everyone's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Chen Manman also agreed with what Luo Xuan said. and follows through with No, we can't eliminate them right away..
Chapter 552, "Branches, 20 Points Each, No More", is the clearest early answer because it turns Ai Xiaochun's situation into a concrete plot event.
Chapter 620, "The Journey to Find a Brother", is the clearest early answer because it pushes Shang Shuyue into a new phase or setting. Early on, After a day of torrential rain, the water level of Dragon Ridge Lake.... By the end, Let me do it." He had wanted to be the team leader for so long!.