What is oral literature?

Oral literature is any piece of work that, instead of being written down, is passed from generation to generation orally. Historically, all stories were passed down in this manner prior to the advent of writing, and many cultures in the present day maintain rich oral traditions. There are many examples of oral literature that you would be familiar with.
The Pentateuch of the Old Testament in the Bible (the first five books of law and history, Genesis, Exodus, Leviticus, Numbers, and Deuteronomy) were traditionally passed on through oral tradition, although Moses did write them down. The first book, Genesis, was carried orally for roughly 430 years from Joseph to Moses before it was written down.
Scholars believe many of the works attributed to Homer likely originated as oral works. Homer is known for widely popularizing and standardizing epics such as The Odyssey and helping to write them down, but it's possible that this process involved other contributors as well.
Finally, to use a more modern example, some have argued that the core story of Disney’s The Lion King is based on a variety of African oral traditions.