My point was that a realistic definition of immortality is having the capacity to live forever, rather than necessarily living forever.

I understand that humans aren't capable of reverting to an embryo and redeveloping endlessly, in a manner analogous to a jellyfish.

But maybe it's possible that there exists some sequence of nucleotides which would enable some human-like species to naturally regenerate specialized cells/extracellular structures, and avoid or repair life-cycle dysregulating mutations associated with aging, to approach something like immortality in a complex organism.