You say it was the last man on Earth... Couldn't it have been a woman? Then they repopulate Earth with 50 of their children and 50 inbred grandchildren and save the human race!...kinda... The human race now has deformities and probably wouldn't last much longer
You should read Y: The Last Man. It is a comic book that follows Yorick Brown and his male pet monkey Ampersand; after every mammal with a Y chromosome dies. It is really awesome.
Taken from the wiki: "What is "Creepypasta? In short, a Creepypasta is a short story that is posted on the internet that is designed to unnerve and shock the reader."