The awoken are humans, slightly altered by life in space, maybe even genetically engineered to function better in low gravity than a regular human. As they were human there is no reason an awoken can not use the light. The awoken are humans, there for existed before the collapse. And you do not need to have been present to be brought back, you just need to be comparable with the ghosts ability to resurrect you. It is not a leap to assume that any race of any kind can become a guardian aslong as they are compatable with the light