I argue that Jacob’s Ladder is a type of “It’s a Wonderful Death” film. Jacob dies in Vietnam before the story starts, but he lives on in a version of the world where he gets to accomplish more of his life, with it’s heart aches and joys. He even meets the American soldier that killed him, although he doesn’t know it and doesn’t really reconcile with him. But is eventually at peace with his death, especially when his son (who died before he went to Vietnam) takes him hand-in-hand to heaven. As other “It’s a Wonderful Death” films have, Jacob’s chiropractor is his guide that helps him through hard parts of his life. However, since Jacob doesn’t think that the lives of other people is necessarily better without him, it doesn’t fully fit into the “It’s a Wonderful Death” model.
One could also argue, as some have, that Jacob is actually dying throughout the film, and he’s just hallucinating. But early in the film they mention a theory that people who die before their time get to live out their lives in an alternative reality until they accept death. That’s more interesting, and consistent, than hallucinations of a dying soldier.