Hyrule is inside of the Light World, which many other kingdoms are also inside of (such as Labrynna, Holodrum, Hytopia, etc) and the great sea is what became of the light realm in Wind Waker, so it would be inaccurate to generalize it as just “Hyrule”. In this same naming convention the default name for Lorule would probably be something like the Dark World, but the Dark World which is a corrupted version of the sacred realm (more on that later). So instead it is the Mirror World because it isn’t even a dark version of anything, it is just prone to misfortune. More on that later as well.

The worlds between are literally that. The worlds between. Any world that is not directly connected to the goddesses like the Dark Realm (not to be confused with the Dark World), the Twilight Realm, the World of the Ocean King, Termina, anything that is a consequence of the creation of Hyrule in order to contain Null.

The people of Hyrule have utter faith in the gods, even to the point of their own downfall. The very nature of Hyrule is that of a cyclical battle between the supposed good and just powers of the gods, and the wicked dark powers of the demon tribe. These two forces pull the land of Hyrule between prosperity and apocalyptic doom. One cannot exist without the other. The legends they speak of are that of heroes ordained with the essence of courage, princesses possessing the wise blood of the goddess, and wizards who are corrupted in their morality by the lull of power and ambition. The three virtues of courage, wisdom, and power, can be viewed as parallel to the three poisons each represented by a serpent, a bird, and a boar respectively. The three poisons keep mortal souls locked in a cycle of death, rebirth, and unfulfillment, just as the three virtues keep the land of Hyrule locked in a cycle that ultimately ends in dissatisfaction.