Call to Arms
Humans, hobbits, and the diverse natural plants and animals that populate the world are all mortal. Even humans and hobbits do not have immortal spirits, there is no promised afterlife for mortals.
Death is an integral part of the Plan of the World as conceived by the gods. Each creature will die in its time, the body is recycled, folded back into the world, while the individual identity is lost. Larger, emergent patterns (ecosystems, societies) continue to grow and change, but only through the individual’s death.
When forming the world, most gods were against creating large numbers of immortal creatures who might someday challenge them. A few gods dissented and went off to create the Fey and its immortal peoples.