How were fairy tales started?

As scary, brutal, graphic, and psychologically abusive means of relaying a life lesson to children. Obviously the Viking fairy tales created 4,000 years ago will be drastically more barbaric and obscene in nature than any of Walt Disney's Fairy Tales, but the same lesson, or new found insight, remains a constant subject matter of content although the context can be delivered exponentially different, from violent and sensual to funny and "child friendly" How they were started, however, has an endless list of answers that nearly all would encompass boredom, socialization, and prestige or to protect one's legacy by passing down stories in the form of exaggerated tales for entertainment or the induction of fear.