Speciation is one type of evolution that has been observed. It is often referred to as microevolution. Macroevolution requires millions of years to be a viable theory. I rejected the evolution of species 45 years ago because I find it illogical to the extreme. The diversity of life evolving from pond scum makes good theory, however it also presupposes that organisms made decisions. It is not only illogical it is statistically impossible or to use a more scientific term improbable.
As to China and language, you are now into another scientific discipline known as anthropology. A central tenet of anthropology is that where cultural traditions (myths) from widely separated cultures share essentially the same details it indicates a historical event. In other words just because you cannot find a flood myth in Chinese but can find flood myths that share essentially the same details in Africa, Asia, South America, North America, Central America, and the Pacific Islands the probability that such an event occurred is extremely high. Now, not all cultures studied by anthropologists have written languages. Add to this that after languages have been reduced to writing those myths are recorded, not before. And yes Egypt and Sumeria both have flood accounts.
The flood took place about 4000 years ago. Therefore the Sumerian, Egyptian, Chinese, and all other extant and extinct cultures are post not pre flood. This brings up another Biblical account that has been shown via anthropology to have a basis in fact and that is the confusion of languages. I wrote a couple papers on flood and other myths when I was in school. It is a fascinating study.
Since evolution is not one of my burning issues I think you need to check out the Discovery Institute for a Biblical/scientific response to the evolution of species. http://www.discovery.org/