Is there any proof of life right after flood?

If you take the CURRENT rate of population growth, then yes the population goes down to one about 5000 to 10,000 years ago. However, current population growth is due to increases in agricultural and health technology which have doubled the expected life expectancy. Also factor in historic scourges like the Plague and other niceties like warfare and you can see why current growth rates should not be extrapolated into the past. Using the same logic, I could estimate the age of the earth to be about 3 months using the doubling time of E. coli (about 20 min) and the estimated number of E. coli in the world. If the world were even a few years old, we would be swimming around in a deep bacterial slop worldwide.