[The Might]

I agree with William Cloud Hickli here, indeed the Rings had the power to preserve, though here just like with the invisibility thing I think it is only a side effect. Why would an immortal Maia want to create a Ring that could enable him to live longer? No sense at all. It was the power the Ring had to create (for example the foundations of Barad-dur) that gave it this power to preserve things and this possibly in the presence of mortals made them live longer.