“Fermi Paradox is a possibility.”
Fermi’s Paradox had a hilarious fatal flaw.
It assumed that advanced technological civilizations would never figure out how to hide themselves as “nature” or “background noise” or “planets” or “moons” when that is the obvious and wise choice.
It also assumed that such civilizations—having mastered the art of camouflage—would never figure out how to “hack” the speed of light and space-time so they could travel anywhere they wanted as quickly as they wanted.
Only stupid species like humans would send out electromagnetic signals signaling their location.
Only stupid species like humans would claim “the science is settled” and the speed of light can never be “beaten”.
The “paradox” would be like Native Americans in the West convinced no white men could ever find them because they were many hundreds of miles from the ocean.
You listed numerous potentially fatal flaws to the Fermi Paradox.
They are all possible.
Another strong possibility: we are alone in the universe.
We have not found any evidence of other civilizations. It may be by design, it may be there aren’t any. It may be there are none close enough in time or distance to be discoverable.
There are numerous very unlikely events that resulted in our civilization. The odds may simply add up to the point other civilizations are highly unlikely, even over billions of years, and the size of the universe.