Interdimensionary aliens would explain a lot, including some potential reasons for their existence.
back to the aliens!It's assumed that aliens are interplanetary or intergalactic, but since you are opening your mind up to options here, what about interdimensionary? Aliens coming from another dimension would better explain how their craft are able to defy the laws of physics so effortlessly.
Aliens could be manifestations of another plane of existence that we do not normally see, possibly the spiritual dimension. What if dark forces taking this form were to counterfeit an account of our origins, claiming to have seeded the planet. Could they win our allegiance if we have already decided that God didn't do it?