What is the style in The Palm-Wine Drinkard by Amos Tutuola?

Amos Tutuola was a Nigerian of the Yoruba people, a once-powerful nation state in Africa. The Palm-Wine Drinkard is written in the style of a folktale, much like the fairytales that most Europeans would recognize. Tutuola is intentionally "borrowing" from the Yoruba oral tradition to tell the story, although it is unclear how much of the story is from the Yoruba and how much from Tutuola himself.
Folktales are typically passed from one generation to the next, not by written text but through storytellers who may add or subtract from the stories they heard when they were children. It is important to realize that virtually all of the fairytales we have in western culture, like Little Red Riding Hood or Hansel and Gretel, were also passed person to person, generation to generation orally and were only published much later.
Obviously, no one can precisely say when a culture's folktales were created, but they almost all contain a moral or a lesson on living, which suggests that they were used as teaching tools, parables to demonstrate the norms expected of members of the tribe (or group, village, kingdom, etc).
The Palm-Wine Drinkard contains almost all of the things we associate most with folktales: magic, a quest, hardships and adversity on the journey, gods and monsters, heroes, villains and strange occurrences that are inexplicable to the characters, all of which serve to illuminate the moral(s) of the story.