The world population has quadrupled in my lifetime, so I would be willing to believe the old bit about “more people are alive now than have ever died.” But it’s bunk. Estimated count of all people ever is 100 billion. There weren’t that many people in the past but our species goes back 50,000 years and that makes it up.
https://www.scientificamerican.com/article/fact-or-fiction-living-outnumber-dead/