That's what I've thought for some time now. What better way to hide advanced aeronautics than let everybody think it's aliens? One story I heard was that the object that crashed at Roswell was a high-altitude spy balloon, and the stuff about aliens was intentionally pushed by the military to throw everybody off the trail.
I’m inclined to think that what crashed at Roswell was an advanced military aircraft.
Does it make sense that Super-Duper Advanced Aliens come across the galaxy with their advanced technoloty and come here to stub their toe and crash? No.
Does it make sense that a military prototype would crash near a military base and get covered up by military personnel? Yes.
Occham’s Razor.