We are told that "Mortals are all animal-origin evolutionary beings of ascendant potential." (underline is mine) And as Adjuster-indwelt mortals, all of us here on Urantia have as our destiny the adventure of one day returning to the Father on Paradise.
The section titled The Ascending Mortals begins:
"The following narrative presents the universe career of an Adjuster-indwelt mortal. The Son-and Spirit-fused mortals share portions of this career, but we have elected to tell this story as it pertains to the Adjuster-fused mortals, for such a destiny may be anticipated by all of the human races of Urantia." (underline is mine)
I think it is safe to say that the majority of humans will follow this career. Of course, there are those who may not, but that remains an individual choice, and one which may not be able to be finally and rightly made until we have passed from death on this planet to the status of survivor.
As to the immediate experience of life after death , I would invite you to view our short and beautiful flash video called After You Die , which outlines in great detail the teachings of The Urantia Book about this fascinating subject."