On other sites, some have speculated that it's a paraphrased version of Psalm 121:8, edited to remove overtly religious aspects.I like the part where Tilly actually recited a prayer (or what sounded a lot like one) as Ripper was being released into space.
Perhaps a succession of crewmembers will, in turn, volunteer to serve as "animate copilots" (they'd have to have a lot of them do it, so as to minimize the possible harm to any one person) for the shroom vroom drive.
I think they clearly established that a human could hook up with the spore drive, though as we saw with Stammets, there are some side effects you probably wouldn't want to repeat too often.
Stamets had to do the horizontal gene transfer first, to even make it possible. He went ahead and did this to himself of his own volition even though it was already said that eugenics experiments are forbidden (nice nod to continuity with DS9 there). So they're already in violation of regulations (or maybe he would be considered to have sole responsibility). I think having more people volunteer to rotate as living navigational computers, and having to get the gene transfer, would just compound this.
Kor