What role did the concept of "invisible realms" play in shaping the mythologies of ancient civilizations?

The idea of "invisible realms" has been a common thread across many ancient mythologies, from the Greek concept of the Underworld and the Norse realm of Asgard, to the Egyptian Duat and the Hindu Lokas. These hidden worlds often represented the unknown aspects of life, death, and the universe, serving as a canvas for exploring the mysteries and moral lessons deemed important by a society. By examining how different cultures described and interacted with these mystical places, we can gain insight into their worldview and the spiritual significance they placed on the unseen forces that governed their lives. How did these alternate realities shape the way ancient peoples understood their existence, and what can this tell us about the universal human need to explain the unexplainable?