The Earth was created by a race of intelligent beings existing in a dimension beyond our own.
One group of these beings, known as Nerds, were masters of mathematics and systems.
In the beginning, the Nerds said, "power up the system", and they turned on their extradimensional computer, and there was light.
Now, the first days of Earth's Creation were kind of like the early days of the Internet.
In the first era, the Nerds (aka Coders) created a Matrix -- a framework upon which their dimensional system would be based upon, after which they created "Terrains" and "Atmosphere."
In the second era, the Nerds created some innovative code which they called, "Lifeforms". The first Lifeforms were simple and rudimentary, kind of like Pong or Space Invaders.
In the third era, the Geeks arrived. They saw something very promising about this dimensional environment, and began to make the Lifeforms more fun and interesting. They coded the Lifeforms with the chance to evolve to higher levels under the right circumstances.
In the fourth era, the Artisans arrived. They began to create ever more elaborate terrains for the dimensional world, and create ever more interesting and complex designs for the Lifeforms.
During the fifth era, the Dudes arrived. They created a more intense battleground for the Lifeforms. The Dudes were the authors of the dinosaurs. Unfortunately, the gaming became so intense that the system crashed and they had to reboot, but they lost most of the data from the eras before.
During the sixth era, the Gamer Chicks arrived. They infused the newer lifeforms with cuteness, emotions and drama.
During the seventh era, the Brainiacs arrived. They were the ones who wrote ever-more-complex strategic and plot devices for their characters. They created complex attributes for their players, such as elaborate social systems, religious beliefs and philosophies. Some of the Brainiac creators were referred to as "Muses".
And therefore this the reason why competition is a way of life for most life forms; why there are many life forms that seem designed by committee; why not all life forms are relevent to mankind; why we see a developmental progression of lifeforms in the fossil record; and why some members of the gaming team have been hinted at in a number of polytheistic religions.