I basically agree with the thought process of the OP.
However I have this twist: All of the humans are cylons.
There are several pieces of evidence for this:
1/ Watch Dee's reactions in the scenes immediately following where she picked up the jacks on Earth. She is clearly in a greater state of shock than everybody else. Then you have the post-suicide scene where Lee is going through her things...and finds a bag of jacks. I think the jacks on Earth stimulated her memory in the same way that the wall did for Tyrol and the guitar did for Anders. Dee realized realized she was a Cylon, couldn't deal, and killed herself.
2/ WTF is up with Starbuck? Either the current Kara Thrace is a clone/download of the Kara that burned up in re-entry or the body in the Viper is a clone of the original Kara and put there by somebody as part of a head trip on Kara (less likely). In the first scenario, there is some form of resurrection hub left on earth or other means of regeneration/resurrection. (I won't persue the implications of the second scenario because I think it is unlikely)
I have thought this for a long time, there just wasn't enough evidence for it. Now there's enough bread crumbs out there that I think this is where the writers are heading.