My own interpretation of the Traveler cards leads me to believe that it's a survivor. It may have built us up as a way of defending itself against the darkness. Though I feel the point is moot when one question comes to mind: why did the darkness leave? It is true that the Vex worship it and the Hive may channel it but why did the darkness itself leave? According to the second Darkness card it was a species ending event that entered our solar system. Our Golden Age ancestors didn't stand a chance, it's followers are here but where did the entity itself go? And why do the Nine (the closest things to the Darkness) stay at distance?