That means, more people than ever working on more problems, with more tools, background knowledge, resources, distinct goals, and collaboration.
This is not even close to being true
The world population increased from 1 billion in 1800 to 7.7 billion today.
I'm not going to do the math but there's something to be said about how many we are today vs. even 200 years ago. But, no, the majority of humans ever born are not, in fact, still alive today...
Most humans ever born, are still alive today. Our population growth over the past centuries dwarf populations of the prior centuries.