It is some people’s belief that life only happens in very specific circumstances in very specific conditions, while it is my belief that life can exist more easily as long as a planet has the right basis for it.
Neither of these sides of this argument can be proven or disproven but whatever your opinion on the matter, there is still a high chance that life would exist elsewhere in our universe.
So yes, it is very likely that aliens are real, even if they were in the smallest forms like bacteria or other single-celled organisms.
But complex lifeforms that would supposedly visit Earth or have visited and somehow the public does not know about their presence is a lot less likely.
We, in our 100,000 or so years of existing and evolving as a species, have yet to reach the point where we could travel to another far-off planet. This means that if aliens on other planets that came into being as complex life-forms around the same time as us would not be able to visit us without more theoretical advancement.
Explanation:
Here I explore several possibilities:
Aliens on another planet have existed for far longer than we did and have had the time to grow and advance and are now an interstellar species that has the capability to cross space to get to us.
Aliens had developed into a complex species on another planet but have been annihilated before we could come in contact with them. (This brings up several topics such as the Fermi Paradox and other questions of why we have not seen extraterrestrial life yet.)
Said alien life has not developed enough yet to reach us and is in somewhat of the same stage as us.
Thinking about alien life logically, it is highly unlikely that planet Earth has come in contact with complex aliens. If you haven’t noticed, the government is not that great at covering things up and if we were to have been contacted by a complex alien race, we would know by now.
UFOs:
UFOs have been a common feature in works dating back to almost thousands of years ago, with flying-saucer-like objects appearing in paintings and weavings from the late 500s.
I have always wondered if aliens were to make a spacecraft, would it look like a flying saucer? And the answer to this is surprising that it is quite possible.
The flying saucer design is extremely handy, all you would need is some kind of balanced levitation system around the bottom of the spacecraft to allow it to hover and it would be able to move in different directions with just a slight tilt. Circles are symmetrical, which means that they would be good for flight if a light material were used. It would be easy to command a flying saucer if you can see all around the craft.
I think this answered your question, I was kind of distracted while writing this so sorry.