Yes, he’s a real person, and he lives in New Mexico:
‘Jack Handey is a solidly built man of 64 with a swoop of graying hair; when he smiles, his teeth are blindingly white. ‘
Jack Handey’s homepage here with plenty more.
And from this ‘Shout & Murmurs’ piece in the New Yorker:
‘Eventually, I believe, everything evens out. Long ago, an asteroid hit our planet and killed our dinosaurs. But, in the future, maybe we’ll go to another planet and kill their dinosaurs.’