The Grays are real, but not from another planet. They are indeed from Earth and are multiverse travelers. They happen to live in a timeline where dinosaurs never died out. But they enjoy visiting our alternate timeline in which humans live and abducted them in their multiversal ships. Their testing base happened to be in the location on their Earth where Roswell, NM is on our Earth. Thus the 1947 crash was indeed their 1st attempt at multiverse travel that went extremely wrong. Earth's governments are helpless to these invaders since their technology far exceeds our own. We are merely lab rats in the eyes of the Grays.
Their culture is is very strange in comparison to humans. They not only do not care to wear clothing but are completely carnivorous. However they are not savage. They will raise small mammals for meat and egg laying dinosaurs for eggs. They are very inquisitive and love to figure out things. Their large skulls support a brain larger than humans. Their huge eyes can see in the dark very well. This is important since they are nocturnal. This is one reason why abduction happen mostly at night.
They have feathers like birds and are warm blooded. They lay eggs and put them in incubators. Females run things in society since they are bigger and more aggressive. The males are more colorful with bright blue feathers. They even do odd mating rituals like birds would with chirps and puffing out their chests.
Since their eyes are different from humans they use a neutralizer to wipe the minds of their subjects. They tend to look down at mammals and think they are inferior since they tend to eat their relatives for lunch. They also enjoy abducting livestock for an exotic snack.
As you can see they evolved from the raptor dinosaurs, specifically the Troodon. They lost most of their tail and snout but still have some claws even thought they are not used too much. They still have sharp teeth and have a huge brain. Their bones are quite brittle since they were once agile hunters. They still have the agility but must make sure they do not get hurt and break a bone.
When they make sounds they can make hypersonic sounds that humans cannot hear. This makes it seem like they are communicating via telepathy but really they are not. In short they are not little green men in the UFOs it is little gray dinosaurs!