There are no new ideas under the sun.
All of this has happened before.
On that note: https://en.wikipedia.org/wiki/Antikythera_mechanism
Could very well be that UFOs are being flown by a branch of humanity that beat us to the punch when it came to developing technology.
They would not need interstellar tech to get here at all if this were the case, all they would need would is enough time to advance ahead of us.