No one seems to mention that the Vex (and the Traveler) are both Vex and are both capable of time travel. This could lead to multiple dimensions, or variations, of universes. I believe someone made a post that said (in short) that the Traveler went back in time to save Humanity, for whatever reason. Also in the Speakers room there are like 6, "replicas" of our solar system. Maybe those are the variations in time and space, the ones the Vex are keeping, "locked" out of time and in our time line the traveler is keeping humanity safe so we can stop the Vex and the Darkness and possibly rid the universe (and all universes/dimensions) of the Vex and Darkness