I am not at all a conspiracy theorist. I try not to work my mind up over anything that has no plausible evidence. And I certainly don't believe this planet, this human race, has ever made contact or covered up contact with aliens, nor do I believe aliens attribute to the ancient wonders of the world.
But I agree you would have to be ignorant to think that this is the only chosen place in all of endless space where water, plants, oxygen, biology and life exists to some capacity.
Even if it's just some near lifeless scavenger microbes just barely surviving off of some type of gas or chemical exchanges in the environment; even if they are only found in one little area of the entire planet that just happens to be able to harbor life, I believe somewhere out there are living organisms occupying another planet.
I truly truly believe before my lifetime is up robotics, space travel, and AI will reach a point where we will know the wonders of our universe.
But in the words of GOAT cartoonist Bill Watterson: "the clearest sign that there is intelligent life out there is that they haven't contacted us yet."