I think that Australia and New Zealand are technically part of Oceania, but it is unclear whether you intended to include their European-descended population, or just the Aborigines and Maori. I will walk through the loophole and put in a good word for A. Bertram Chandler, whose first story, “Giant Killer,” is a classic about intelligent rats on a spaceship (guess who the giants are). Chandler wrote a great many well-constructed, entertaining, SF potboilers. He was an authentic ship captain in the merchant marine who wrote during the long nights at sea, and when he docked at New York, he would visit John Campbell, the famous editor of Astounding, carrying a bundle of manuscript with him.
I have several hundred volumes of folklore, myths, and legends from around the world, one of my finest subject collections. I’ve taken a quick cruise through them to find some of the the ones I remember best. One of the best folklore books I have ever read is James Izett’s Maori Lore. Izett was Scottish by birth, but a New Zealander by adoption who compiled the work on behalf of the government. I have no idea if it is in print, as my copy is a first edition from 1904. A very large, famous collection that I have only read parts of is The Legends and Myths of Hawaii by King David Kalakaua. Alice M. Terada (Hawaiian) wrote a nice collection of stories with brief notes, The Magic Crocodile and Other Folktales from Indonesia. A recently acquired collection that looks fascinating (but I haven’t read it yet) is Never and Always: Micronesian Legends, Fables and Folklore, by native college students.
Perhaps the most memorable African work was recorded by a French folklorist, D. T. Niane, who collected it from the lips of an old griot (bard) in Mali: Sundiata: An Epic of Old Mali. An enjoyable collection written by a native is The Orphan Girl and Other Stories: West African Folk Tales by Buchi Offodile.
There are many others, but I either haven’t read them yet, or they are written by Westerners.