Here's what I don't get. So these aliens travel thousands of light years to get here. They don't want to be seen and are on secret missions, to probe folks and cattle, yet their ships have tons of flashing lights? What they can't fly in the dark?
For the folks that say they are here for our water, minerals, etc. There is water everywhere in the universe. Hell, there's more water on some of the moons and asteroids in our solar system than there is on earth.
is there life on other worlds? I believe so. In our lifetime we'll find life within our own solar system, microbial maybe, or primitive celled, but I think we will.
Have we been visited? No, I don't think so. The distances are just too vast even if you travel at the speed of light. Unless you can bend space or create a wormhole, but the energy needed to do something like that is enormous. If we detect a message from space we could respond and maybe 400 years later they can respond and then us....and so on.