First Ancestral Race
The First Ancestral Race are mysterious, god-like progenitor aliens, never seen during the course of the series, who created the beings known as "Seeds of Life" to sow the galaxy with life forms. Two such Seeds of Life were Adam and Lilith, the only two Seeds that we know of (though there were multiple Seeds). Adam and Lilith were transported across interstellar space in massive vessels dubbed Moons, Adam travelling in the White Moon, Lilith in the Black Moon. Adam's mission was to directly procreate the Angels, who would then become the dominant species on the planet upon which Adam landed. Lilith's mission was to arrive at her destination and spread LCL, the "primordial ooze" from which what humans would consider "normal" terrestrial life forms would evolve, culminating (after millions of years of evolution) into humans.
However, two Seeds aren't meant to land on the same planet. Adam was the first Seed of Life to occupy the Earth, but 4 billion years ago the Black Moon containing Lilith violently collided into Earth (simply by accident), in the event later dubbed "First Impact".
The First Ancestral Race also created the artifacts known as the Spears of Longinus, awesomely powerful weapons built using their technology. A Spear was paired with each Moon as a countermeasure should a Seed abandon its mission, become too powerful, or to take the initiative should two Seeds occupy the same planet.
The First Ancestral Race are actually the true authors of the "Dead Sea Scrolls": the information was included in White or Black Moon transport vessels as a safeguard, along the Spears of Longinus. What became known as the "Dead Sea Scrolls" was essentially a manual the First Ancestral Race sent along with each Seed of Life, detailing how Seeds of Life and the Spears of Longinus work, as well as predictions about the future in the event that a Seed is awakened. The idea was that if ever two Seeds landed on one planet, the inhabitants (most likely the progeny of Lilith-type Seeds due to their intelligence and use of science) would eventually find the manual-artifact that came along with a Seed, and use the instructions to put one of them back into dormancy (in the event that even the Spears of Longinus of both Seeds were disabled). However, the Scrolls eventually came into the possession of the mysterious Seele organization. Seele abused the knowledge they obtained from the Scrolls about Seeds of Life, the Spear of Longinus, and Angels, and embarked upon a plan to bring about a forbidden fusion of Adam and Lilith which would elevate themselves to a state of godhood.
Details about the First Ancestral Race, including their ultimate motives and aims in seeding the galaxy with life (if indeed they had any beyond simple altruism), remain almost totally unknown. They are described as a "humanoid species" and it is stated that they were "the first extraterrestrial intelligence". Whether this is simply referring to the fact that they existed before humans and Angels, or whether they were literally the first species to achieve sentience in our galaxy, is unclear. Although the First Ancestral Race was active four billion years ago when they spread the Seeds of Life through the galaxy, whether they still exist in the present day somewhere in outer space, have long since gone extinct, or if they have transcended to a higher level of existence, remains entirely unknown. However, the legacy the First Ancestral Race left is still present with Adam, Lilith, and the progeny of both; as well as the Dead Sea Scrolls, Spear of Longinus, and the GeoFronts (really, the White and Black Moons they created) which are described as being "nearly identical" and "clearly artificial". They are also briefly alluded to in Episode 20 when Gendo Ikari tells Fuyutsuki that an intelligence other than humans created the GeoFront.
The First Ancestral Race are the ultimate creators of humans as well as Angels, and from the perspective of both, could well be considered "gods".
Notes
- The First Ancestral Race is thematically similar to the "First Born" aliens from 2001: A Space Odyssey, the alien race that created the Monoliths. While the First Born did not outright create life, they were the first race in the galaxy to achieve sentience, and in their travels across space set up experiments to try to encourage the development of sentience on planets where they encountered life (i.e. with proto-human apes on prehistoric Earth).