Interesting topic!
Biology first, let's face it humans are squishy things and anybody who has gone 7G plus in an aircraft, will understand the limits of the human body. So if one references the reported maneuvers of the UAP's, then:
1. it isn't man made,
2. it is man made, but un-manned, or
3. it is very high tech which provides damping for the human pilots.
Nikola Tesla had designs for a UFO like aerial vehicle, or so the story goes. And these designs disappeared as soon as he died. Many of Tesla's ideas and designs did and do work, even his idea of wireless power distribution. So who is to say that his "UFO" did not/does not work.
The rise in UFO sightings, after his death, may be a clue. But who has the tech?
The Germans, during WW2 were working on "The Bell", designs and tech all disappeared somewhere.
So these UAP's could be man made.
On the other hand, the case for other worldly visitors can also be made. Many ancient writings, include sections about incredible flying machines with powerful weaponry. How could these ancient writers, imagine such technology?
"Sky people" also feature heavily in many ancient and not so ancient cultures. No way of knowing if they were on something or simply speaking the truth. When you watch some documentaries about this, the latter option seems quite plausible.
I, for one, question how some ancient structures were built with amazing precision, with simple tools like hammers and chisels. Otherworldly tech?
And as noted above, these UAP's have amazing maneuverability. Much, much better than any known man made aircraft.
I saw a headline today which went something like this: Are we not simply the ants, in someone's experiment?
Obviously, with the USA defense and FBI asking for more money to counter this possible threat, there will be no big reveal, as many UFO lovers were hoping for.
Anyway, my 2 cents.