I think the end goal is not to extend the life of our (inherently flawed and limited) biological bodies, but to replace them.

We aren't going to explore & colonize space in fragile meat bags that require food, water, air, stable pressure, gravity, and temperature. Even on Earth, supporting a ballooning population isn't going to be easy.

The goal is to digitize consciousness, and there is still a lot to figure out before we get there. I don' think it's possible to make human bodies as we know them "immortal"