Guardian is just a fancy title like Iron Lord or Warlord. Felwinter never did anything like the other Warlords, but was still called one before joining the Iron Lords. The Iron Lords were just Warlords with hearts. Guardians are just Iron Lords with a bigger army. And all of them are just Risen with motivations. But the Traveler has to choose the Eliksni to bear its light, so until they earn its love, that won't happen.

I don't think the traveler has much to do with it. I could be wrong of course but I've always see the ghost as a kind of immune response from the traveler to look for potential protectors. Giving us the light would make us the target of the enemies of the light and we would naturally fight the enemies of the traveler. The reason there have been no risen of the other races is the ghost recognize them as enemies of the light so don't bother scanning the dead to see if they can be risen. Without some form of support anywhere a risen of the other races would still just end up in the hands of the enemy. So as we make allies and there are places the risen can be taken without immediately being used against the traveler, the ghost will likely expand their parameters of what can be potentially brought back.

I see where you're coming from but Ghosts only resurrect humans for a reason. Human being blanket term for humans, exo, and awoken, that is. Humans are the travelers chosen. Eliksni, for all their faith, never got the power humans have. On top of the traveler being afraid of Rasputin's retaliation, humanity has fought tooth and nail to protect the traveler and destroy the Darkness. Eliksni looked to the traveler to provide everything. Cabal don't care one way or the other. Ghosts aren't going to start reviving those races just because they're fighting for the light.

The reason the eliksni never got powers was because there was no need for it. The traveler got away in time with them. Here it got injured, we're not the chosen or favored, we're what was available. It also has nothing to do with what the person did in their past life, crow or the baby that was resurrected, or the kind of person they would be, a lot of the warlords, all the ghost has to do is find a hint of light. If they can find light in machines created with the help of the darkness, exos, I don't see why there wouldn't be any in a cabal or eliksni.