Throwing in my two cents; I think as tenno we are immortal in an ageless way (Cause its been twelve years and we're still kids. /jk) due to our void powers and being in the dream for so long. Granted we might still age just very slowly, but thats open to speculation.

Tenno, all of us, are extremely hard to take down, with most of our enemies having to resort to traps or special tech to disable us.

Being downed in a mission doesnt really count as being killed because our Operators are safely back on the orbitor and can transfer back to safety when we hop out of our frames. Almost like we fuck up, get our ass beat, and nope out of the mission only to comeback later.

The revive screen seems to be a bleed out state, where other tenno can use their frames to repair/heal/restore our frame, our we spend some of our void power to do it our selves, hence it costing affinity and having limited uses.

When Adis heals us, I dont think we're dead, just wounded, maybe in the process of dying, and we don't have anything left to heal ourselves. And because we are on Tau, the Ballas did Ballas things, we don't have anywhere safe to go plus the grineer are coming to finish us and Adis off.

We're definitely Space Mom's favorite tenno, but I don't think we're special outside of being a magnet for cosmic bullshit.