The Phoenix is a circle. A circle put in place by the universe. The destruction of it results in it's immediate re-birth in the red-hot-room.
The mightiest of giants can be felled by a small boy with a stick, cloth, and a small stone. Humanity is no exception. Eventually, through natural disasters, mutants, extraterrestrial life, supernovas, war, whatever.
Humanity will go extinct.
It is the same fate ever species, ever individual ever created shares. Sure, two identical people in personality, memories, and from the same place may start off the same. Everyone and everything does.
But getting from point A to point B isn't the same every time.
"The only destiny that everyone shares… is death."