> bacteria/viruses from thousands if not millions of years ago will most likely not be able to bind to our cells.

When the white man arrived in South America and in Australia the diseases they carried devastated native populations.

Even though in the case of Australia they had been separated for over 50,000 years.

HIV came from chimpanzees - evolutionary distance 5 Million years.New influenza strains regularly come from chickens and pigs.

So what you are saying is complete nonsense.