The Traveler

"very few of us survived, and those who did, owe their lives to the Traveler."

-Unknown Narrator in the Destiny ViDoc

Origins
The arrival of the Traveler sparked a golden age on Earth in which it's inhabitants spanned the Solar system, whether or not the Traveler is an physical entity, AI or Deity of some sort is unknown as are it's origins.

Present
'' "legends say the traveler sacrificed itself to save us, the mysterious sphere still hangs where it made it's last stand, low above the earth,  keeping silent watch." ''

-Unknown Narrator in the Destiny ViDoc

At the end of the golden age, humanity was attacked and all but completely wiped out when the Traveler sacrificed itself to save a small portion of humanity and as it hung low in orbit a civilisation was rebuilt in it's shadow, temporarily safe from the alien threat.