Alright, so I understand the basics - survival of the fittest. Those with beneficial (for the current environment) traits survive and breed, meaning their traits get passed on to the future generations.
But what about those who didn't have those traits? Let's take penguins as an example. Penguins are black from one side, to blend in with the water as seen from above, and white from the other, to blend in with the water as seen from below. But how did this come to be? Did a random "white belly" mutation occur in one penguin gigachad, who proceeded to breed enough female penguins to create a stable population with his genes? What happened to all the all-black penguins? Did they go extinct from their inferiority? Well, they somehow came to be in the first place, so their color must not have been extinction worthy.