Lets use some logic.
The distance between us and the next nearest system is light generations away. so that would require an absurdly long living creature that wouldn't go mad with boredom.
So a piloted craft is out
OUR satellites are so good they can be used to read the paper, so there's no need for a craft to come within our own eye sight.
There is nothing here that is not out there unless they are coming here to eat. And since no one has been eaten and no vast regions of crops destroyed....
Two dimensional thinking has been the downfall of many. Just because we do not know how to travel to other star systems in a timely manner, does not mean others can't do it. I am not saying yea or nay, just that we don't know what's out there. Do you know how big the galaxy we reside in is? I don't either, but they say our entire solar system (which by the way is HUGE!) exists in one tiny speck of it.
These drawings out in South America, are indeed a mystery, as are many ancient remains of things. How did the ancients create and move precisely cut 50 ton pieces of rock? I don't know that either, but they or someone did it. The evidence is there.
There are many theories floating around that suggest, while the speed of light may be an unsurpassable constant, other forms of locomotion may be possible. One such possible means is wormhole travel. Einstein himself expounded upon this is his treatise on the Einstein-Rosen bridge. Also, "they" seem to think that some form of inter-dimensional travel is possible.
One theory I have heard about where these aliens come from is the moon. Yes, the moon. The theory suggests that the reason we didn't ever go back to the moon is that we found structures there, and that is where the little grey aliens come from. This sounds like a nutter theory, but hey, is it really anymore far out then FTL travel and aliens watching us for the last 200,000 years? Not hardly.
BTW, if aliens have been watching and studying us for hundreds of centuries, WTF are they waiting for?

I mean how long do you have to study something before you go down and say, "Hey, take me to your leader!" also, what we may be seeing is our own miltary playing around with newly developed craft that are uber-top top top secret. Some people say that we have craft right now that we have used to go to Mars, and made the round trip visit in less than 2 weeks!
But they are rumors and such. Let me tell you about rumors. One year at the prison we had all heard that come the new year, the prisons contract was going to change and among the many many changes, we would be getting new, more with the times, uniforms. I hated the old ones that were white shirts and blue pants. Suck-o! Well the assistant warden had a meeting one day and was telling us all about the changes. I said when do we get the new uniforms? She says, "What new uniforms"? LMAO.
So much for rumors.
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