I think you're absolutely spot on about the "living" vs. "not dying" WRT Jadis. I didn't read LotR until college, but Jadis was very much the model in my head for the effects of the rings over time. That and the Greek myth of Eos and Tithonus.

And I'm fascinated by Christmas-as-solstice for the reason that it's always winter and never Christmas in Narnia. That actually resolves one of my major long-term irks in the series as a long-standing resenter of Christmas's ubiquity. (I have an "always christmas and never winter" tag.)