Dear vulcan42,
Nearly there vulcan but not quite.
Mankind invented god(s) to explain our existence. But there was a snag! Mankind realised that we die and decompose (oops).
Hence a new app had to be added to the fairy-tale so that human life is not just a fleeting spark while god or the one-time gods happily played games with the new toy: the eternal universe, minus us! Unfair!.
Along came a smart-alek and said: we must have an invisible, massless but concious entity hidden inside us which leaves the rotting flesh on death. Someone, in answer to what to call it said: "Let's call it the "soul" - that should keep the people happy on the opium.
And so the soul came about.
However nobody thought about its detailed make-up except it cannot leave the body when the body is alive. So it can only consist of the self at the moment of death - another bloomer as it's the worse time to chose.
A new fix required.
SIQ.