In order to repopulate the entire earth in less than 10,000 years, people would have had to make thousands of babies overnight and migrate out of Turkey-- or where ever the hell the ark was supposed to be-- at incredible speeds. Running like cheetahs in every direction, while leaving no record whatsoever of having done so.
At the same time they would have to create all the separate cultures. Changing into all the different racial and language groups along the way. Adapting to arctic, tropical and temperate environments, domesticating different varieties of plants and animals. Making sure that the big brown people went to the Pacific Islands, the short black people went into Central Africa and the tall pale folks went to Scandinavia. Separating and intermarrying to get the DNA mixed just right to confuse later scientists into thinking that humans evolved over millions of years.
Once arriving in their new locations, the people would have to get busy, busy, busy. Learning how to build different kinds of housing and make different kinds of clothes from various local materials. Isolating themselves on remote islands, and mountain villages. Creating different religions, artistic forms, family structures, healing practices. Inventing weapons to make war with other groups.
(We are of course leaving out the part about all the animals and plants and birds and insects and diseases having to somehow organize themselves by sub-species and migrate to their correct locations so they would be there before the people got there. I would love to hear a "creation scientist" explain a)why there are no monkeys with tails in Africa, b)why there are penguins only in the southern hemisphere, c)how freshwater fish got to the rivers and d)how arctic lichen walked from the Middle East to the Russian tundra. I won't be holding my breath while I listen to the crickets.)
After doing all that in record time-- and planting lots of fake archeological evidence--everyone on the planet would have to forget having done it.
This would make for a cool science fiction story, only it would be too improbable for anyone to believe it....