Why do you believe there have not been ‘retrievals’ over the last six decades? There are witnesses to them. I know one personally and I do not believe he would make up a fairy tale.
Shot down, or crashed? Either would be possible, I suppose. I know a guy that believes the UFOs are from a spiritual plane. He’s described his sightings to me, usually in proximity to military bases. What he describes sounds like afterburners, to me. But he believes in them. He also smokes a lot of weed and claims divinely inspired dreams.