But how do Gilgamesh, the Swordsman, the Anachronauts and the Priests of Pama fit in?

Source: https://bleedingcool.com/comics/marvel-comics-full-april-2023-solicits-solicitations/

Gilgamesh has appeared in multiple Holy Grail Wars, and he is by far the strongest Archer-class Servant in the series.

Source: https://gamerant.com/fate-series-strongest-characters-all-anime-shows-movies/

Half a dozen of the main works are deliberately in dialogue with literary classics and ephemera, from sources as diverse as Mark Twain’s satirical monologues, James Joyce’s erotic letters, the Epic of Gilgamesh and “Antigone.”

Source: https://www.nytimes.com/2023/01/05/theater/under-the-radar-festival-influences.html

In the case of Gilgamesh, the hero was the subject of many of humanity's greatest myths.

Source: https://www.cbr.com/avengers-best-secretive-members-marvel-comics/