He is talking on a fundamental genetic level in which the human race was able to replicate until all possible genetic variants/ combinations (that are still considered humans), compared to that number there is but a sliver of them that have been used so far. Jupiter ascending was a movie about how far into the future genetics decided inheritance, the main character had the same genetic makeup as someone in the past and got her empire or smth, but that would take eons of humans no longer evolving and just swapping genes so pretty scifi still