Humans probably cant see Aliens because they don't perceive them as such. Example a human that tries to be nice to a wild or domesticaed gorilla or chimp is looking for trouble. He or she will get their face ripped off. Even if that human brings food and medical aid for the chimp.
Most apes are worried about being alpha and dominating a strange like clothed ape. The ape's mind can't reach the human mind level but only for brief periods.
Most humans are too are like apes because of ego status - is me or my team winning!?
I make more money than them-you, I can bench more than you, I smarter, my team is winning, I have more friends and money. Status, status, status. Me strong-right-better you weak-stupid.Man has limited linear line thought definition of what an alien should be.
Most men are not open or capable of perceiving an alien as of yet. Like the apes in the jungle man and woman can get obsessed even with things even with ideas. "I am going to win and dominate" is the manamal instinct.Man would be like psychic vampire or funny pet to alien.