The most plausible explanation for Roswell was Project Mogul
A less plausible explanation is the idea that the U.S. government was conducting high altitude tests on Japanese POWs
And the least plausible explanation is aliens.
I am not 100% but, I think this book touches on a theory that really makes sense if there were oriental looking aliens.
https://www.amazon.com/Body-Snatchers-Desert-Horrible-Roswell/dp/0743497538
The original book I read basically stated that they believe the US Government was testing what space would do to the body and were sending prisoners of war into space using balloons. And who were the number 1 prisoners of war in the US in 1947? Japanese. The US literally had concentration camps for Japanese Americans. At first they claimed these camps were closed in 1944, then 1945, and then 1946. Later they said they weren't exactly sure when they all closed. The Roswell crash happened in 1947.
But, the book theorized they were using Japanese prisoners with medical conditions to test what happens. They raised them up, let them die in space, and hoisted them back down. And, the Roswell crash was one of these tests where the tether broke and they floated away, not making it quite high end to kill them and they crashed. The "aliens" were Japanese prisoners who were tortured and caused Hydrocephalus. Which was basically a death sentence back in the 40s.
Of course, just an idea, like every other idea of what really happened. It's likely to just be Project Mogul and the alien bodies were just eye witness lies... I will see if I can find a free copy of that book somewhere. Or perhaps a synopsis.