According to the books of sorrow, the vex where accidentally brought into this dimension by Crota after having been tricked by his sisters. Also, the traveler was originally a sentient moon of Fundament (Hive homeworld,) but was attacked by the hive after being corrupted by the darkness themselves in an attempt to escape their planet before it was destroyed. Adding the hives origins would clear up quite a lot of info about the vex, traveler, and hive. Rasputin was awkwakened post collapse by an unknown person The falle(truely called Elinski,) came to the solar system post collapse, in an attempt to steal the traveler, as the traveler once gave them a golden age, but fled when the darkness came, letting the majority of Elinski die as a buffer. And lastly, the exos where originally made ALONGSIDE the warminds as a physical army controlled by their hiveminds. Once the majority of the Warminds where destroyed, most of them became able to think for themselves, as they no longer had a controller. After this, Rasputin decided to let his free as well.