If the alleged human-like extraterrestials (the
Pleiadeans, for example, which have been supposedly "witnessed" by thousands) somehow exist, it would be virtually impossible for such beings that look like us to have evolved independently on other worlds. This would be the most spectacular example of parallel or convergent evolution in the history of animated nature.
"virtually impossible" is not the same as impossible.
Birds and bats both have similar body shapes as a function of the vaguaries of flight. In detail they are dramatically different, but in overall gross aspect they have marked similarities.
IF one assumes that UFO "visitations" are anything but human imagination, and IF one assumes that any "aliens" have ever actually been witnessed by humans and those aliens actually had
2 legs
2 arms
2 eyes placed forward looking on the head
on a central, upright frame
it would only say that:
1. Bilateral symmetry exists (which it does across many unrelated animals and plants)
2. Binocular vision is a valuable asset that can be achieved with minimal number of eyes = 2
3. There is a 50/50 chance of upright versus horizontal stature
If we are to find shocking examples of parallel evolution would it not be just as shocking to find that we share bilateral symmetry with some plants? Or would it shock us that stereoscopic vision is something we share with dogs?
(Frankly, while I have little doubt that there is life somewhere else in the universe, I am rather more skeptical of aliens visiting earth. In some ways, precisely because the witnesses invariably describe something that is "understandable" to us as being a fellow cognizant being. It would seem far more likely that our imaginations, hardwired as they are to respond to the "humanoid" --seeing human faces in clouds, anthropomorphizing our pets, etc-- would be the prime generator of such experiences, rather than cases of amazign parallel evolution.)