Again, your right
They were there, then the flood, then came Noah's blood line.
But remember, we all agree that man changes over time, that adaptation is possible and maybe even necessary.
Unless you were there to see exactly how Noah's descendants looked like, you can't really say that their different.
Nether you nor anyone else, has that genetic information.
Actually, we do have that genetic information. We have tons of samples from people from thousands of years ago, including before the supposed flood.
Before the flood, they show clearly different groups of people in different areas - native Americans in the Americas, Asians in china, Europeans in Europe, Africans in Africa, and so on. Then, right after the supposed "flood", we see the same types of DNA, in the same areas described above - as if the flood didn't happen.
That's the opposite of what we'd see if the flood had happened, since suddenly, at ~2500 BC, the old pattern would vanish, and after that all people would have very similar DNA, all being descendants of Noah.
DNA alone shows that the flood myth didn't actually happen. Many other pieces of evidence also show that the flood could not have happened. Many more can be found here:
http://www.talkorigins.org/faqs/faq-noahs-ark.html
Many of those were known 200 years ago. That's why Christian geologists scrapped the idea of an actual flood decades before anyone had heard of Darwin.
In Christ-
Papias
P. S. Gotta "hand it" to the handy man - impressive show! Let's give him a hand..... : )