No, it's golden age, mystical, quasi religious bullshit. At no time in the history of mankind or any other animal for that matter has the perfect time ever existed. As hunter gatherers we were prey to the seasons, random natural disasters, microbes, virus and disease.
As our bodies immune system, hampered by all the other expenditures on its resources (fighting each other, running away from big shit, keeping warm/dry etc.) is still a wonder of nature, so are all the organisms evolution throws up to exploit the reserves of energy and supplies that are us. We hold no special place in this system.
No one is arguing that a healthier non polluted existence is not a boon to our chance of survival, but complete invulnerability is bollocks.