The way the UAPs seem to work is by manipulating gravity, something we know to be possible given an essentially unlimited supply of energy. That changes the physics and possibilities of things like interstellar flight. Having that capability doesn't necessarily eliminate mechanical error, to say nothing of crashes as a result of intentional attacks, etc.
But to the point, are they aliens?
We have allegedly tracked these objects visually, on video, and by numerous electronic means. If that's true, it limits what it could be.
- One of the more likely explanations is it's all just made up. All of the evidence and testimony is falsified. It's just some sort of long term PsyOp.
- Another possibility is it's some sort of electronic weapon that can spoof a lot of sensors to make it appear to do impossible things.
Aliens are more likely than some of the other sci-fi explanations like time travel or interdimensional travel, which require some restrictions on the actions of future or extradimensional counterparts that don't seem likely.
Aliens are the most exciting prospect. Your government sucking seems more likely.