Given that UFOs have changed and evolved much like the Grilles of a Chevy or Ford since the 50s, I suspect that these are of human origin, but nobody is prepared to admit it yet.
If one had mastered intragalactic space travel, I doubt you’d monkey with the design too much, but hey, maybe if they are aliens, they, too, like to pimp their rides.
The emerging consensus is that the aliens do not use “intergalactic space travel”, at least through “space” as we understand it.
In addition there is an emerging consensus that they have been here longer than we have.