Before humans existed, life was already present on Earth. The seas and the land, the great skies above, all teemed with life. Earth's ecosystem was in harmony. Of course, this does not mean that life was peaceful, the lions ate the lambs, the sharks the fish, and so one, but it wasn't disruptive. Prey greatly outnumbered the predators, and were only killed to sustain, or beget, the lives of the predators. No matter the actions of any living being, the cycle of life would continue as strongly as ever.
Then the gods became bored. Watching, as the wheel of life, the never-ending cycle, went on and on for aeons, became boring. Their perfect creation, became mundane. And so the gods created another being, made it sentient, taught it the concepts of race, religion, class, but most of all, an innate sense of superiority over the rest of creation. They called it human, and set it loose upon the Earth. Ever since, the gods have been watching. Not interfering with the world, but watching it slowly burn as their creation, their playthings slowly break the cycle of life. As they poison the Earth, consume those who roam it, and burn themselves in the fires of war. The gods aren't good, the gods aren't evil. They are fickle, creating the perfect world, only to see it set ablaze. And we're here for their entertainment.
Bonus:
Long before living memory, long before history was even written down, there lived a girl whose story has been passed down over the centuries. Her name was Iris, and she lived amongst a people that identified themselves as the Phronean, the people from Phroneo. From a young age, this little girl showed extraordinary wisdom, beyond her years. So much so that, at the age of seven, she was asked to sit with the council of elders, to help govern her village.
Iris was especially valued, as she spoke of the nature of life, and the role of mankind in it. She saw, how the different tribes of humanity, the different states and peoples, were either destroying themselves, or destroying everything around it. She preached peace, peace between humans, and peace with the rest of the world. Though the villagers of Phroneo valued her wisdom, their sentiment wasn't shared by the wider world. You see, the world Iris lived in, was one consumed by war. Villages fought each other, tribe versus tribe, state against state. And though the Phronean, inspired by this wise young girl, stayed out the fighting, they were attacked.
A nearby tribe, less keen on knowledge and wisdom, known as the Machean, from the village of Machos, attacked Phroneo. Looting and pillaging through the village, slaying everyone in their path, they found Iris at the well in the central square. She did not fight, she did not run, and neither did the villagers around her. She saw how violence destroyed her world, and that fighting, no matter how just the cause, would eventually tear it apart. And so she stayed behind, even when she encouraged, even when she begged others to run, she stayed behind, and awaited her fate.
The gods, seated on their thrones in high skies, saw the sacrifice of this brave little girl. Saw how the world they intended to burn, was still trying to fix itself. Saw a glimmer of the perfect creation they destroyed, a glimmer of wisdom, in a world thrown into chaos, and wept. Wept at the sight of one so small, so fragile, yet rivalling the gods in her wisdom. And as Iris lay lifeless in the village square, the clouds tore open. The tears of the gods rained down upon the Earth. And from the well in the village square, were a wise little girl breathed her last breath, a rainbow appeared. A circle of colours so very different from each other, yet together forming a thing of the utmost beauty. A permanent reminder to everyone, gods and men, that while we are all so very different from each other, when we work together, we can make the most beautiful things happen.