Aliens not seen

Highly evolved aliens may not need to travel physically, but instead astral project.They simply copy what they want of us, as information, and then recreate it out of local material. Moving mass is inefficient compared to just moving the needed blueprint.

We may not have seen aliens yet as they have no need to manifest themselves physically and in fact may have discarded their physical bodies as unnecessary. This may be a common way point in evolution before individuality is discarded.

Part of the big bang may have involved the casting off of the one mind into the many minds, possible with the goal that all eventually re-converge.