There are many cultures in our modern world that do not have a written language and there are ancient cultures that had a written language whose history is clouded in myths.
As to evolution, it is ludicrous for anyone to reject evolution within a species or speciation since this can be has has been observed. Here is an explanation written by tuppence who is better equipped than I am to answer your concerns:
Animals can speciate today, especially if their mating cues are visual. Because dogs and horses and cows are happy to mate with anything that smells 'right', they remain one species each. Birds and fish, however, will speciate rapidly if a portion of a population is isolated long enough so that it starts showing up with inbreeding 'markers' like a spot someplace, or a color change someplace.. Then, because these animals use visual cues for mating, along with seasonal cues, they will refuse to mate outside their own recognizable sub-group. So a new 'species' is born. Hummingbirds are an excellent example of this. Lots of species -- and many with virtually identical DNA and appearances so close it takes a real expert to tell which species an individual belongs to!
Evolutionary biology is a theoretical branch of science that lacks any empirical evidence to back it up. The hero of evolutionary biology is time, and when science sticks to what can be observed, tested with experimentation, and depends on data and not speculation it can be shown that time is relative to the speed of light. What evolutionists and secular science does not want to address is that lightspeed is not and has never been constant and has decayed over time.
You might find this site of interest:
www.setterfield.org