Why is it so inconceivable that we (humans, on earth, that is) may be the only "life form", at least as we know/understand it, in the entire universe at the present time? That seems like a perfectly possible, and perhaps even likely, situation to me.
The reason I say this is because I think that if there is indeed other advanced "life" out there, it's likely not very friendly (and therefore, chances are, it would come find us for destructive purposes). Think about it, everything we know about the universe and "life" is destructive at some level. All life forms on this planet compete in some fashion, and most do so in a devastatingly cruel manner, for example. Getting eaten alive is SOP in nature on this planet. If you're not eaten alive first, then the second you can't move under your own power, then you're soon to be somebody else's dinner. The human species isn't that much different than the other species on this planet, at this root level. Why would it be any different on any other planet, if there was in fact life on other planets?
At a galactic level, everything is pretty much in chaos, at least on a galactic time scale. These orbits we're in are merely a temporary toilet bowl effect before a cataclysmic demise, so, where there looks to be order and symmetry and harmony, there isn't if you just wait long enough.
If we think that there are super intelligent and compassionate life forms out there that just want to study us for the intellectual learning, I find that extremely unlikely.
I've never seen anything in my life that isn't explained by the physical world as it's clearly understood. I thought I saw a ghost one time when staying in a 700 year old house in England some years ago....it really did look like a ghostly apparition...but the next night my wife clued me in that it was just the effect of the occasional automobile headlight from off in the distance shining through the really old glass in an odd manner. I was quite relieved.
Maybe some people see things, or have been abducted (and "probed") by visiting aliens, but I'm not one them, thankfully.