Doryphoros's left leg is bent, his toes lightly touching the ground. He is turned slightly, in a relaxed pose, and his head is shifted to the right. The image is an icon of athletic strength and prowess. The Ancient Greeks glorified human strength and athleticism (hence the highly renowned Olympic games). Man is made into a champion, hero, and god.
The contrapposto pose alone, I think, gave the statues more than just a relaxed, "natural" look; it gave the figures an air of confidence and swagger. With this new-found freedom from old rigid forms came a sense of pride. The Riaci Bronze Warriors make for a good example of contrapposto.
These guys were discovered by an Italian man named Stefano Mariotini who was spear fishing on vacation in 1972 when he saw a human arm in the sand (kinda creepy). They were found off the coast of Riaci, in Southern Italy. They resemble human beings but are unrealistic. The legs are too long, and the body is split in half with an exaggerated groove. Their backs are too tense, and their muscle tension is physically impossible. They're also missing a tailbone. The reason for this? The statues were made to look more than human. If it was just a statue of a normal human being it would have been too boring. They exaggerated to enhance the aesthetic experience, and perhaps to enhance their own idea of humanity. These are, so to speak, "more human than human." They are god-like. Why are most Ancient Greek statues nudes (at least those of males)? It was all a part of the admiration of humanity, of the human body, physique, strength, etc. This was the Classical Period.