summary of my analogies
new eridu is a simulation, it's actually all one big "hollow", and the hollows in it are just the source code becoming corrupted. but it's an intentional corruption— a test.
phaethon is the one doing the simulation. it's possible that they're the only one even alive in it, and everyone else is just a memory, an ether construct of a person who once was.
it's all literally a game, and the "hollow" that is new eridu is...life. phaethon's directive is to guide people through the hollow, to find a way out of it— to guide them both through hollows and through life.
to navigate it, both hollows and life, they need a massive amount of "observation data"— for the hollow of life, this is memories. the video archive, the signals they search for and store in their archive/workbench. with enough data, they can plug it into the maze-solving algorithm, which i think must be literally embedded into phaethon via their connection to the HDD.
their goal is to finish the game after having accomplished the objective: find a way out of the hollow. it's to reach the endgame, the truth. and if they haven't helped humanity overcome the hollow by that point, if they ~crash the chariot~ again so to speak, then the game resets and they repeat it until they succeed. the endgame, the truth, is in the center of hollow zero.
(oh, and i believe the "truth" is death. probably that everyone is actually dead, and the hollow of new eridu is therefore essentially an afterlife. that's why the exaltists are so hellbent on achieving spiritual immortality and disregarding life.)