So it had always confused me that in the Greco-Roman myths Juno/Hera was always married to Jupiter/Zues but for the AC universe Ubi chose Aita, the Etruscan version of Hades/Pluto, as her husband. It wasn't unitl Origins that I possibly got an answer: Serapis. Due to being ruled by both Greek and Roman empires a lot of Egyptian gods were combined with their Greco-Roman variants. Serapis is a combination of Osiris and Apis on the Egyptian side with Hades/Pluto and Dionysus/Bacchus on the Greco-Roman side. Serapis being a form of Osiris was married to Isis. This is where Juno/Hera comes back in because she was seen as a variant of Isis. Ergo Juno married to Aita, a chthonic diety, rather than Jupiter, a sky god, whose counterparts were the various Ra-Amun-Atum-Ptah syncretisms, sharing the eagle, bull, and ram as sacred animals.
As told in the AC universe the Osiris myth Isis with the help of Anubis used the Ankh PoE to resurrect her husband for one night and conceive a son, Horus. So far however, the power we’ve actually seen from the Ankh is the ability to record a digital impression of a person that can be accessed later.
Combining that information with Juno's background it’s not hard to imagine that she stored Aita personality with the Ankh and then later tied it to the genome of a human, making the first Sage. Help from other Isu is possible as Anubis (and Thoth) are seen as the Egyptian version of Hermes Trismegistus. The place that Aita's personality was stored could be similar to the Grey or the Egyptian afterlives. That first Sage would later be known as Horus to the Egyptians. Their mythology is a bit of a mess with there actually being two Horuses, the Elder and the Younger. The Elder is sometimes paired with Isis with the Younger being a reincarnation of him. This also works with the lore surrounding Aita and the Sages, as Osiris and Horus the Elder can both be aspects of Aita and Horus the Younger, a reincarnation that replaces the former.
But is there a specific person that Juno would have used as the template for the first Sage? Someone whose family she might hold a grudge against. I am of course talking about Cain and Juno's hate for the human rebellion led by Eve. Cain has already been mentioned as a proto-Templar and bearing mark. Clay said the mark was the Templar cross but could it have actually been the heterochromia that afflicts Sages.
A lot of the mythology surrounding Cain work within the framework of the Sages/Horus. Cain’s descendant Lamech is said to have entered the same unholy pact as Cain, possibly meaning he was the next Sage/Horus. There were four generations between Cain and Lamech which coincides with the four sons of Horus. Lamech himself also had four children of his own. Furthers myth give Cain horns as part of his mark. Horned individual appear all throughout mythology and legends with an important one being Alexander the Great, another suspected Sage.
The generation after Lamech is when the biblical Flood occurred. If we don’t take the dates surrounding the beginning of the Human-Isu war and the Toba catastrophe as exact, the Flood could correlate with the First Disaster. While Noah was probably not a Sage his son Shem could have been. A Sumerian Sage, a descendant of Shem, from 3000 BC identified by Abstergo possibly had a connection to the Flood narrative via the contemporary Epic of Gilgamesh. Another Sage, the Wanderer can be linked back to both Cain and a Persian ruler, possibly Xerxes or Cyrus, another "horned" individual.
Ideally, Ubi would have addressed some of this in CotP, Origins comic, and the end of Uprising. Have the Ankh be the PoE responsible for the curse and Bayek send it to Aya in Rome. Have Aya give it to Lugos. Have Juno go into some detail about the Grey and the creation of the first Sage. Other than a slight snag about where the Ankh was originally found in the Cycle 1 comics, these four different media would have been neatly connected together for a more compelling narrative.