Eternity came into existence when the universe was formed and spontaneously assumed the collective consciousness of all things living in the universe. He is the incarnation of time as his sister Infinity represents space. They have two other siblings: Death and Oblivion. His children are Empathy, Eulogy, Expediency, Entropy, Epiphany and Enmity. Collectively they are known as the seven Friendless. As one of the forces of reality, he remains one of the most powerful and nigh-omnipotent characters in the Marvel Universe.
Although the complete activities of Eternity are unknown, it is known to appear when threatened, such as for example when Thanos assembled the Infinity Gauntlet.
He is, along with Death and Galactus, one of three fundamental entities in the Marvel Comics Universe (the Living Tribunal is further above them all and maintains the cosmic balance of power). The absence of Galactus would allow the emergence of the antithesis of Eternity, Abraxas.
External links
Information about Eternity (http://www.classicmarvel.com/cast/eternity.htm)
Captain Marvel, on the other hand, was not only human (the editors tagged him "The World's Mightiest Mortal", perhaps in a slap at the Kryptonian), he was a kid in a man's body, thanks to an old wizard and a magic word.
From the very beginning, Captain Marvel's chief artist was the man most identified with him throughout his career, C.C. Beck, a grand and wonderful cartoonist whose style was perfect for the character, somehow capturing exactly the essence of the boy inside the man which was fundamental to Cap's innocence and naïve lack of sophistication.
All the other Marvel stories were told in the more simplistic, cartoony style of Beck, Costanza, and Shaffenberger; Junior had his adventures illustrated by Raboy, one of the finest realistic artists in comics history.