|Time for some|
|My grandmum used to say....|
Spirits are purported disembodied beings - wandering minds without the physical connections -- pure intelligence or thought. Many religions see them as what remains after one has died. The idea of spirits may have arisen from the awareness that something seemingly "non physical" and distinct from the body is what animates us. If one cuts off my foot, or my arm, or any part of the physical me, there is still something left. Some cultures define that essence as a soul, others a spirit, and still others as both. This duality, of physical body and 'soul' leads directly to the belief that consciousness will somehow continue even after the very organ of consciousness, the brain, has turned into worm-ridden tapioca pudding.
Most cultures posit some form of invisible spirits which may or may not be benevolent, but which generally all share the same characteristic of being an invisible friend or foe, that's not quite a deity, but not quite mundane.
 In the Bible
The Israelites of the Old Testament did not postulate the survival of the identity after death until the injection of Hellenistic ideas, especially Plato's "ideal forms". Just as an actual chair was held to be a poor copy of a perfect "ideal" chair which existed somewhere in a remote mathematical mindscape, so was the psyche held to be the ideal, "true" human being, temporarily imprisoned in a corruptible body. These ideas of a dichotomy between the mind and body filtered into the Levant and were embraced by the Pharisees in the 1st and 2nd centuries BCE, even as the Sadducees retained the Hebrews' original lack of belief in spirits and angels.
Against this background, aided by a Greek translation of the Jewish scriptures, Jesus Christ fashioned a proselytizing variety of Judaism which was further refined by the dualistic ideas of Saul/Paul of Tarsus. This in turn set the stage for further developments by the Catholic Church which firmly entrenched the idea of man's soul as an immaterial entity, incapable of annihilation yet subject to being bound in bodies or physical places like purgatory or hell.