Only those few who are able to surpass their fear of death completely can fully experience the highest forms of life; not the mundane life of the mortal, but the godly life of the resurrected.
Shapeshifting requires the ability to transcend your attachments, in particular your ego attachments to identity and who you are. If you can get over your attachment to labeling yourself and your cherishing of your identity, you can be virtually anybody. You can slip in and out of different shells, even different animal forms or deity forms.