So to go back to the original question of alien intervention and the afterlife, it comes down to what we believe about the nature of a human being.
It is my belief that the material/physical aspect of our being is manifest from the elements of the physical universe (anciently; we are from "star dust"), but all the subliminal, mental, intangible, emotional, etc. aspects have manifested from those fore mentioned root races in the process of the evolution of our soul.
From the simple one cell organisms of ancient history, our flesh has evolved over time. But when a sentient soul began to involve itself with our organism, we had become a combination of life entities (Theosophy) on a far greater scale.
What remains for us in the physical, is an ability to become symbiotic with both our self and with any other community of other life entities.