We don't know what happened to our ancestors. Anything from environmental disasters to epidemics could have wiped out 95% of our ancestors at some time, and th

We don't know what happened to our ancestors. Anything from environmental disasters to epidemics could have wiped out 95% of our ancestors at some time, and the only trace of that would be slightly lower fossil counts. In other words, "our ancestors survived" isn't really reassuring. There's a really wide gap between "Everybody's lives become seriously harder" and "Humanity goes extinct". After all, even WW2 only managed to kill ~3% of the human population. A completely survivable event.