Game Informer has an interesting feature that assembles what’s known of Destiny’s (admittedly often murky) story thus far, which they’ve gone so far as to fact check with Bungie:
The Last City gets founded. Humanity is scattered across Earth, and all our planetary colonies are presumed lost. Guardians rise across the planet, and small, scattered pockets of surviving humans begin to search for the Traveler. Led by Guardians, these pilgrims seek a fabled refuge beneath the Traveler, and a community begins to form there. The burgeoning City is doing pretty well for itself, but it’s not long before trouble shows up. The Fallen have pursued their Great Machine (the Traveler) across the stars, and once they find it on Earth, they prepare to attack.
Destiny has taken a lot of criticism for the story, as it’s been related in the game, but there is definitely some quality worldbuilding going on here. Seeing it assembled in a more linear comprehensive fashion gives me some hope that the next installments of this game might prove to be more interesting, narratively.