I've seen many UFOs in my relatively long life. In most cases I've found a reasonable explanation for these sightings, but sometimes the explanations are only provisional. The best one was an actual flying saucer, and I've posted that one here in the past, together with the provisional explanation.
And yes, I've very hopeful indeed that there are advanced alien civilisations in the universe, possibly an infinite number of them. I just think that when and if we meet them, they will tell us two things; firstly, that they are not responsible for any of our UFO sightings, and secondly, that they have UFO sightings of their own.
And I've experienced other paranormal events, and I really don't have any provisional explanations for those, except human fallibility (and I could be wrong about that).