In the 1990s, the CIA commissioned a study to discover what the most terrifying, but believable "alien" image they could come up with would be. They settled on (as usual) plagiarizing everyone for the past century, like the lazy niggers they are, but realized that making the eyes extremely large, pure black and distorting the facial features created the most uncanny and terrifying appearance (this is literally why moths have eyespots on their wings - it indicates a predator is in the danger zone and you should flee). The fact that the image was vaguely human introduced familiarity which increased the terror. Then they started spreading stories about "abductions", which induced nation-wide panic, creating thousands of "abductees" who had somnambulic nightmares, convinced these events really occurred, despite being loaded with physical impossibilities that clearly never occurred, but are common in dream states (walking through walls, giant objects floating over towns that only the dreamer can see for some reason, being anomalously naked despite not remembering undressing, missing time, etc.).

Thus the "grey" was born. Ever since they've spread rumors that they're fairies, demons, interdimensional space lizards, humans from the future, alternate apes that evolved in tandem with humans. But what they are and always were IS FAKE. They're fucking made up.

Additionally, the Betty & Barney Hill case was created to normalize mixed race black male/white female couples by pairing it with an outlandish story, so the mixed race couple would be seen as more normalized by comparison.