Ufology, presumably you actually do know that
no one has demonstrated how unicellular life arose on earth by natural means?!
There are various guesses about abiogenesis, but none has prevailed. Even the
RNA world hypothesis, which edged out DNA world and protein world, has problems. Francis Crick, of double-helix DNA fame, got to the point of simply ignoring the abiogenesis problem. But that did not stop him from speculating that unicellular life was purposely sent out into the universe by intelligent agents unknown, and that some of their algae supposedly arrived on earth – i.e. directed panspermia. So, just to reiterate:
Abiogenesis, i.e. unicellular life arising by purely materialistic means, is
unexplained by science.
That means that your pronouncements about the scientific soundness of life arising elsewhere, eventually becoming intelligent and then developing technology and traveling to earth is solely
speculation, and is not based on
empirical science.
On top of that, the vast majority of the scientific establishment discounts the idea that earth is
currently being visited by alien craft. You claim scientific credibility for alien craft, but the science establishment denies this hypothesis. If, according to
Big Science, the view your hold is unscientific, then you might consider toning down your "scientific credibility" shtick. Instead you'll have to actually support your claims with compelling evidence.
Then on the other hand, with all that's now being discovered about the quantum world underlying our macro perception of reality, there may be
direct linkage between the "normal" world and what is relegated as "paranormal." Perhaps.
By the way, for future reference, it would probably help focus the discussion if a specific collection of sighting reports, or some general review, by whomever, is taken for discussion. Otherwise, one person might relate to sighting reports that others reject, and vice-versa. Condon Report? Nicap? MUFON for 2015? Davenport? Passport to Magonia? I wouldn't have a good idea.