In the seventeenth century, Emanuel Swedenborg wrote that he could talk to creatures out of this world, which he deemed as angels, and which, according to him, lived in the rest of the planets of the solar system. During the early thirties, a young Orson Welles did a radio adaptation of H.G. Wells' nineteenth century bestseller War of the Worlds by pretending that the world was actually under a Martian attack. Whether this anecdote was true or not, the fear of an alien invasion grew big during the fifties, which led to a series of unforgettable B-movies, such as Ed Wood's Plan 9 from Outer Space, which will always raise a laugh to geeky kids, quirky teenagers, and awkward adults.
Our collective imagination of beings from outer space has increased enormously during the last few decades, giving us superb works of fiction like the Alien series and its thrilling follow-ups. We're already in the process of starting expeditions to colonize Mars, yet there seems to be no sign of any extraterrestrial civilizations trying to contact us. Lately, a new theory about this has popped up: perhaps humanity is just too dull for aliens to be interested in us.
This depressing and plain theory has been proposed by Doug Vakoch, who is currently the president of METI —Messaging Extraterrestrial Intelligence–, which specializes in detecting signs of intelligent life across the universe to establish contact with these beings. As of today, METI hasn't been able to establish any sort of contact with life beyond Earth. However, the laws of probability support the idea that there may be life beyond ourselves, because of the vastness of the universe. Let's not forget that, as Neil deGrasse Tyson points out with lucidity, there are more planets in the universe than the sum of all sounds and words ever uttered by every human who has ever lived.
Vakoch's theory about the alien apathy towards humanity comes out as a sort of side note on the renowned Zoo Hypothesis, which is itself an answer to the Fermi Paradox. This Paradox can be summed up in the following question: if the probability of an existing advanced civilization that can visit Earth through interstellar travel is high, why hasn't such a civilization actually visited Earth and made contact with humanity? Furthermore, what the Zoo Hypothesis states is that aliens actually avoid communications with Earth to allow its natural evolution and cultural development without interfering in it.
The resulting theory can therefore be summed in conclusions that will depress any human who's proud of their cultural and technological development. Vakoch considers that aliens don't find us interesting at all. In alien's eyes, humanity is nothing more than a minor league team expecting that the big guys will someday lay down their eyes on them. It's likely that aliens may actually monitor our civilization, but they are completely unimpressed of what they see in us. Hence, in a sense, aliens would be like an apathetic teenager looking at a caged animal in a zoo. They look out for us, but they actually see us as lower and beastly creatures. In case we do something that may catch their attention, they might as well establish contact with us.
Vakoch also believes that life beyond Earth can be radically different from how it is here, and it can even go beyond the our expectations. Because of this, he believes that the presence of water is not actually a compelling sign of life. Furhtermore, the astrophysicist believes that establishing contact with alien civilizations is possible, and he considered Denis Villeneuve's Arrival a "radical" film because of the acuity of the scientific concepts it portrays. As the film shows, the biggest problem humanity would face in case it suddenly came in contact with an alien civilization would not be an invasion, but communicating with these beings, so different and distant from us that they haven't reached out to us because we're not of use to them just yet.
The New Yorker
If you're interested on the infinity of the universe and all of the possibilities that it holds, be sure to check out the great Carl Sagan's explanations on why we're made out of stardust. If you're interested in how the human species is making itself obsolete, take a look at the debate if machines will be able of placing themselves over human poets.