Fermis paradox is not that mysterious to me. People do not understand the vast distances that must be traversed in order to get from Earth to the nearest star other than the sun. It is dang near impossible for a mere life form to travel that distance intact. Maybe better to say “impossible.” Of course that does not rule out radio contact or perhaps even unmanned rockets making the trip. But maybe we just haven’t yet come across that.
If by all the known laws of physics we understand if we could conceive and construct a craft that could achieve the speed of light we wouldn't get less than a quarter of the way to the nearest star and everything and everyone we left behind on Earth would be long gone.
I think Fermi assumed that some civilization would have become advanced enough to build self replicating probes to fill up the galaxy with their presence over the course of millions of years. Maybe he just assumed that the desire to explore/expand is common or universal but was wrong, it’s really exceedingly rare.
Freegards