I wonder from what age this statement stops being true; 55? 45?
"Of all the people in human history who ever reached the age of 45, half are alive now" may be actually not far from the truth either, we are just too many now, compared to the past.
On the other hand, the death rate for people born after 1945 is staggeringly low compared with any other cohort in history. If you look at periods later in the 20th and early 21st century, mortality rates are even lower.