10 to the 69th power is such a ridiculously large number that just listing the zeroes doesn't do justice. If you had 10^68 grains of sand, it would be enough to build hundreds of thousands of Earths made entirely of sand (Earth has ~10^50–10^51 grains of sand on all its beaches); it's similar in...
I think when he said "his world is no more" it's more of a cultural thing. likely hundreds of years have passed and the human civilization he grew up literally changed into something unrecognizable. I'm sure humans are still alive