Was the fall of man necessary for spiritual growth? Or, was it a mistake and are we eternally fucked?

I don't believe it was necessary. The good news is that whatever you believe of reality - mainstream or gnostic/archons/alien stuff, the Christ spirit allowed for our salvation. There are a lot of details that can't be known, and are hotly debated.... but overall, I believe that the Christ spirit pierced through our reality (prison planet?) And opened the passage to go back to the Father (land). Since there is apparently no such thing as time, everything is happening at once, the passageway is for all people past and present.
I think we probably still have to find our way to/through the passage, but at least it is there.

There is a reason that Christ above all is so hated.

Another part of the process appears to be sacrifice. For some reason (perhaps) this plane requires sacrifice. And blood is powerful. But that is just a side theory of mine. Christ's blood was so powerful, no blood sacrifice was ever needed again. But some groups don't like that...

Tibetan teachings show how to remain energetically entire after death and remember how to choose the right path to exit Samara (reincarnation/the illusion/prison planet etc/loosh farm).