I don't care what the beings look like, that is no proof that they are Extraterrestrial. What is the simplest, and therefore most likely situation, that explains people being allegedly "abducted" in large numbers AND also explains why the "Alien" Descriptions Match?---Remember it was only after 1977 with the "CE3" movie did the standard "Grey" become a public icon image.---And these things were going on BEFORE 1977.
The only organization that can operate at such a scale is the US Government , Agencies like the CIA and NSA are most likely involved.----But why? Again the most logical reason is that people are being examined and "tested" in secret., most likely because of some kind of weapons test or accident, involving Toxic, radioactive or Biological elements, that would cause a scandal or even public panic if word got out. The victims are continually, being drugged and examined. ------The agency also likely uses a "Dummy" or "Animatronic", fake "ALIEN" to further scare and confuse the victims and make them less likely to talk if the amnesia drugs should wear off---and make them also less likely to be believed if they do talk.----This is the weak point in the secret. This is why the ALIEN DESCRIPTIONS MATCH. Which gives the abduction reports a degree of veracity---As no two people would "invent" the same "Alien" if they were all lies. This also leaves this secret open to dissection as described above.-----While it was a genius idea to use a fake Alien to confuse the victims, they should have used DIFFERENT dummies---so the descriptions did not match, and the reports could be easier dismissed.
So in conclusion, we may conclude, 1) there ARE no Aliens. 2) the government is the entity doing the testing in secret to avoid Scandal or panic, and 3) Some kind of weapons test or accident, or unethical experiment has taken place to make this abduction project necessary.
Yes, "Stretching things" a bit, BUT which is MORE logical? Actual Aliens invading and abducting people, or A government agency trying to hide and control the results of a serious health threatening accident or unethical experiment? My vote is for the latter.