And I mean spiritual in the way a person has spirit, does something spirited. Like leaving their partner or their job, and feeling empowered and vital, at least for a while.
Possibly, when you make those rare, spirited, major decisions in your life, like volunteering in Africa or joining the navy, the universe splits in two, and your spirit can only be in one place, so it follows your spirited decision into the new universe.
The old you stays behind, essentially a clone of you but minus your spirit. That you is unaware that anything happened, aside from a nagging feeling you weren’t bold enough. That shell of you continues on as before, and nobody notices any difference, except for in the long term, and your lack of excitement and excitability is put down to age and just being a normal human who cooperates with what society expects.
Back when we were hunter/gatherers, such spirited decisions happened rarely, maybe to one person, once a generation, in your group. It was rare for a new universe to form, and consequently, within your group, almost all of you were people with spirit. That made an ineffable but powerful difference to your life experience, community bonds, peace, calm, and perhaps your group’s interactions with nature.
As the numbers of humans grew, as we drifted from our birthplaces, as our numbers of connections grew and life became insanely more complicated, then more spirited decisions are made (still perhaps only one or two per person), which meant a constant splintering off into new universes, and few spirited people remaining in yours, with you. Most of the people around you could be seen as NPCs (non-player characters), people operating on autopilot, missing the spark that might draw you to them. This is a negative way of being as a society. Try not to listen to those who are no longer spirited in your universe. Trust that you are still spirited, because for all you know, the non-spirited you that you left behind is incapable of even considering such possibilities, that are not awake enough.
OF COURSE that asks the question, when the new universe forms with the spirited you in it, did other spirited people come along with you? If so, that means that the spiritless you is left behind in a spiritless world, so what is the point?
CONSEQUENTLY this makes no sense in a physical world, and works if we are in a simulation. A new universe can retain every aspect of your old world, and your old world can retain every aspect, expect the you, there, has lost their spirit. In this case spirit is an attribute or ability, as in a RPG, like mana, and not a soul.
All simulations have a computational cost, and it is a reasonable presumption that a universe without much spirit left in it, is turned off. OR, the strength of the required spiritual decision keeps increasing, to reduce the number of worlds running.