Mine is probably the most boring: There are many intelligent species in the universe. Faster-than-light travel, however, really is simply impossible, meaning that there cannot exist a truly interstellar civilization. So while some species have probably settled solar systems other than their own through generation ships, suspended animation, time dilation, or whatever, their range of expansion is limited. This means that encounters between species of different planets are rare. Humans will most likely never contact any intelligent alien species, at most one or two. We might, however, discover evidence of their existence through telescopes or something.
After some thinking I don't really have an answer for the rest of your points on the Fermi Paradox, so fair enough.
Guess I'll just go all in on the UFOs then and point out the following: per this excellent paper (https://www.mdpi.com/1099-4300/21/10/939/htm) going over a number of quite credible UFO sightings that are - at minimum - radar-visual sightings, the objects in question displayed acceleration sufficient for interstellar travel by way of exploiting relativistic effects.
Even the slowest estimated acceleration among the objects would be able to (from their perspective) get from TRAPPIST-1 to here in only 58 days, and from Proxima Centuari to here in only 43. The highest acceleration observed, 5000 g, would mean that (from their perspective) it would take 1.4 days to get from Proxima Centauri to here, and 1.7 to get here from TRAPPIST-1.
If the sighted objects are aliens flying around, then if they didn't care about the timeskips (and there's many reasons they might not, maybe they don't age, maybe they're automated drones or robots, maybe they're nomadic, etc) that's a very workable speed for interstellar travel.
Ooh that paper looks exciting. Imma go give that a read. Thanks!