People have died for as long as imagination has existed. Death is a franchise that services every religion and spirituality, but it's more of a commerce thing. When Wolfgang Amadeus Mozart died, he became a set of box seats at an undisclosed opera house. When Arthur "Big Boy" Crudup died, he became a song – I can't tell you which because of afterlife copyright issues, but it's a good one. Underrated, actually.
Many artists become works. Ella Fitzgerald became a tune that homeless children in Hudson, New York used to entertain each other, while Rodney Dangerfield became a Yo Mama joke. It's hard to become your own eulogy, and thus it's a prized afterlife.
But it's not the only option. William Penn became a doorstop, which seems blasphemous to some, unless you were privy to some of the conversations he let drafts into.
Albert Einstein became an equation, and not the one you'd expect. He became "2 + 2 = ?" on the first test that a young boy was taking. That boy is a physicist now. There's a bureau looking into whether that's permissible.
Lao Tzu became a road, but one that cannot be walked.
You don't have to be famous for your death to mean something. I'm fairly certain the telegraph, electric battery and iPad were built out of people you've never heard of. A funny kid who never did more than sketch clouds became the kite Benjamin Franklin flew to test his theory of lightning – or he turned into the folk tale about it. I'll have to look that up.
Often the living do the dead wrong. A river of starvation victims became an ocean of grain – though because there is no reincarnation, live people must harvest and deliver that grain in this life. They must or they dishonor what the dead become.
Many people die angry or hurt, which is why there are so many bullets in the world. Every modern war has been a thunderstorm of the deceased yelling about their unfair shake. Anyone would rather become vengeance, but you can't become an intangible. That's just not possible. Your physicality begets a physicality, and it's your lot to become a bullet fired at the wrong person. The living don't even know how unhappy murder makes the world.