Short answers, pulled from the story.
The 8th century Vespasian Psalter records the Old English word seola meaning self, life, or animate existence. This earliest attestation anchors a concept that has persisted across millennia of human thought.
Buddhism generally teaches the non-existence of a permanent self while contrasting with Christianity's belief in an eternal soul. The doctrine of anatta evolved from two main philosophico-religious beliefs: eternalism and annihilationism to reject dualism.
Plato was the first thinker in antiquity to combine various functions of the soul into one coherent conception during his dialogues. He considered this essence to be an incorporeal eternal occupant of our being who decides how humans behave.
Avicenna wrote his famous Floating man thought experiment while imprisoned demonstrating human self-awareness without sensory contact. He concluded idea of self is not logically dependent on any physical thing making soul a primary given substance.
Parapsychologist Duncan MacDougall attempted scientific experiment determining if soul had weight using patients from Haverhill Massachusetts. This experiment sought to measure the physical properties of the immaterial essence of a living being.