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.
I think all that is proven is that our senses are very limited.
It is our ignorance that fuels the Fermi Paradox.