That is fine, but my assumption is supported by the history of literature. We don't see anything as complex as Dostoyevski's Crime and Punishment or Twain's Huckleberry Finn in 1000BC.
> Complex oral tradition could have led directly to complex story-telling literature. All it would take is someone writing it down.
Are there any examples of "complex" oral tradition that stand in contrast to simpler oral traditions? Could we compare the early Christian oral tradition with, say, Hopi oral tradition to determine which is more or less complex? I don't think this makes a lot of sense, but I would entertain supporting argument.