The world is not flat and it did not start out in darkness. There was light everywhere. Mass energy kept this light going for billions and trillions of years. Then light began to unravel.
Explaining this one must think of a battery, sort of. After a time a battery will grow weak and the energy of it will make light dim or whatever it is charging will grow slow and eventually stop/grow dark. The vast light in the beginning began to experience black out dots as light began to lose energy. Light properties that went dark began to get mass as in dark holes. The more dark masses that broke off began to accumulate and these masses began to bond together eventually becoming rock like. Then after more billions of time. So called planets began to form as the universe began to grow darker. Remaining light sources became known to observers as suns. These suns were enough to spur life on because pure light was too much for life to exist. As in words like blinding, intense, burning or imaginative language for over abundance of light.
Darkness began to creep more and more throughout. This was the first unraveling. The unraveling of light.