A long time ago our forebears practised what we would call sorcery: they cast spells to influence the spirits of nature. Some were better at this than others were, and yearly contests were organised to make sure that the tribe at all times had the best suited to be their sorcerer-king and sorcerer-queen. The king was selected based on his skills, strength, intelligence and good health. The queen was selected based on her innocence, patience and beauty.
We know this May couple and the May contests from both our fairy tales, mythology and traditional songs.
With time it became clear that the sorcerer’s spells didn’t always work, and some societies changed: rather than rely on the spell-casting skills of a sorcerer, they began to address the spirits more directly, and simply asked them to comply. When doing so the hermaphroditic spirits were athropomorphised and given a name and gender: so the spirit of lightning was called “Lightning”, in Scandinavia Loki (“lightning”, from the PIE root *luk-), the spirit of thunder was called “Thunderer”, in Scandianvia Þórr (“thunderer”), etc. The trees and animals these spirits had originally been associated with turned into the attributes of the deities. So Þórr’s temple was based around an oak tree, and his carriage was said to be pulled by goats. Freyja’s temple was based around a cherry tree, and her carriage was said to be pulled by cats. Etc.
The society was still penetrated on all levels by the idea of sorcery (‘sympathetic magic’) though, so in order to gain the powers of the deities man – i. e. priests and priestesses – could simply impersonate the deities. E. g. by dressing up as a goddess, by impersonating her, by taking her name a girl became her, and thus also gained all her powers. The gods and goddesses of the temples were thus very much real: they were there themselves! Listening to the prayers of man, eating the sacrificed animals, healing injured men, and being pulled or carried around to the fields to bless them, etc. The deities were real! The sorcerer-king and sorcerer-queen were thus replaced by the god-king and the goddess-queen, but not much changed, really.
Yearly contests were still organised to make sure that the tribe at all times had the best suited to be their god-king and goddess-queen. The king was still selected based on his skills, strength, intelligence and good health. The queen was still selected based on her innocence, patience and beauty.
The winners of these annual contests were given an apple. The aging man stood no chance of winning an Olympic games type contest against younger and stronger men, and the aging girl stood no chance of winning a beauty contest against younger and more beautiful girls. Thus the deities were kept young forever, by the help of Íðunn’s apples.