A Plague of Survivors

We are descendants of survivors.
"The last point in which Homo sapiens sapiens hit a dangerous low, coming close to extinction, was at year 70,000 BC during the Toba catastrophe. Estimated human world population (Homo Sapiens in Africa) - between 1,000 and 10,000 breeding couples."

But then we became a plague, we are 7 billion.

And I will continue to be another one in the plague.
How can I (my body) be fit to be the only one in the world (survivor) and at the same time be fit to be one in 7 billions in the world (plague)? And between one and the other, the biggest mistake: we have learned to talk. We became we, a we. The we is the plague. It's the plague that says WE!. The survivor doesn't talk...