Simply put, science ignorant people will often grasp at nonsense ideas because they lack an ability to understand. Space aliens as in "little green men" or aliens disguised as humans per usual scifi?
NO. That noted, it may be aliens have established bases deep in our oceans that are still mostly unexplored. If so, they are likely to be in a process of exiting our world and nearby solar system bodies before being discovered.
If one means "intelligent aliens" one needs to separate the meaning of the term "alien" from primitive alien life. For 2 decades, leading astrobiology scientists have expected primitive alien life is likely common while intelligent alien life is likely rare. In the next decade, this person expects positive confirmation of humans finding primitive life or at least certain signs of such elsewhere within our solar system. Expect that to be DNA based. I posted an ignored thread yesterday about panspermia that gets to the heart of the current status:
Drill for Improving Speaking Enunciation
In more recent years, evidence has increased supporting such conjecture while many now expect advanced alien entities that actually visit our world will be non-organic or at least mostly so because space is so vast with light speed a known limitation, that it would be far beyond what organics creatures could endure in traveling between worlds. So the former scifi expectation of "little green men" or "big headed grays" is receding.
In any case, average understanding of vast numbers of ordinary, relatively science ignorant people, will always lag what more current and knowledgeable scientists themselves think. So asking ordinary people has limited value. I've posted a few times herein links to the 2000 best seller astrobiology book that was a key in the paradigm change of how scientists think about alien life and it is telling that none here on this board have even offered comments much less do I expect anyone actually bothered to obtain the book. On the other hand, books like the Harry Potter series, with its magic nonsense or the comic book level science superhero universe, are popular with ordinary people.
Rare Earth: Why Complex Life Is Uncommon in the Universe - Wikipedia
With robotic AI entities, they might be turned off for distant travel and automatically maintained through long journeys with robotic maintenance and part replacements. A fully self contained, self maintained robotic space craft created by an intelligent race of entities hundreds of millions of years old in a vast galaxy could send such machines out and within a few million years have mapped and come to understand their whole galaxy. I have in more recent years leaned towards the idea that even intelligent non-organic AI entities are more likely to have synthetic organic core brain elements because such may be the way to create the best "thinking" moral mind. Sort of a Borg concept without the "hive" facet.
That in fact, may be a reason why UIEs if such exist create organic worlds in order to evolve such organic brains. Supporting that view, in the Bible at least according to its scripture, Jesus, is promoted by God, to even lead his ancient Angels. I lean towards intelligent aliens visiting Earth, then using DNA technology to improve humans. The result was the Adam and Eve genetic line where they were able to live hundreds of years. With access to the "Tree of Life" they may have received substances that could not be created with organic bodies that kept them alive far longer. By Noah's time, those experiments ended and their genetics were henceforth diluted with ordinary humans.
The Bible itself relates this beginning at Gen 4:14 as Cain is outcast to "land of Nod" where he meets his wife then fathers Methushael. Of course, religious authorities misinterpreted that scripture because they wanted to believe Adam was the first human. Utter primitive human nonsense, given archeology and genetic science and the fossil record. Note, nowhere in Genesis does it state Adam was the first human as in home sapiens. They would have at least removed the pure Adam lineage DNA to an organically compatible off world planet to continue their work and that is where I suspect Jesus's DNA came from 2000 years later that they had to physically implant in one of Mary's eggs.
