This Movie is set in the afterlife. Heaven, sort of.
The basic idea is once you die your soul is transported to a second life (you know...afterlife.) The twist is that everyone's soul is also transported to the same afterlife, like there is a Heaven and everyone goes to the same one regardless of religion. In this afterlife, no one dies (or can die) so the second-existence-universe is comprised of every person and animal that ever lived.
Comedy: The movie focuses on the everyday (not so much everyday, there is no sky/sun/stars in this universe so no time, technically) afterlife of a recently deceased 21st century man. The movie follows his afterlife while explaining how a universe made up of everyone who ever lived manages to exist. How would Adolf Hitler and George Washington interact in the same universe? Jim Morrison and Nikola Tesla? James Brown and a Terror Bird? An infinite amount of new friendships could be made and lost.
Oh, and it could be animated, you know, for children.