I suppose it is possible for aliens to exist, though I have no idea why anyone thinks aliens have a desire to visit earth. A species technologically advanced enough to reach this planet would probably be extremely intelligent and have no use for us.
It is interesting to think about all the historical alien enounters though. Alien like objects appear in ancient art and the concept that extraterrestrials exist isnt new. For example: When people began to accept the modern version of the solar system way back when, after they discovered the copernican view wasnt correct, a lot of people worried about aliens for religious reasons. If earth wasnt really the center of the universe, then could that mean they were wrong about being alone as well? That would challenge the beliefs of the time.
I personally dont believe in supernatural stuff, but when it comes to aliens the statistics just dont support the idea that humans are alone. The universe is waaaaay to be to be so presumptuous.
I mean, stuff like this can surely be a hoax:
But what about things like this? Where you can see the man and dog looking up at the object in the sky. And this painting is old too: Painting of the Madonna and Saint Giovannino
And this is even older: 5000_Year_Old_Australian_Aborigine_Painting.jpg
As for the attention whoring rednecks, they are full of it, in my opinion.