There is nothing "correct", "intrinsic", or "functional" about aging. That's conflating evolution with lack thereof. We evolved to sustain a reproductive cycle and propagate ourselves. That evolutionary optimization has no direct bearing on the specifics of how we age. What we know about aging so far indicates that it's an accidental byproduct of many side effects of the functions of our systems, including the hormonal system that governs puberty, the immune system, the metabolic system, and the higher order DNA management systems (epigenetic programming and replication). None of those side effects are in any known way selected for by evolution, and most of them seem to be tunable to achieve far more durability or regenerative capacity out of our bodies than we are currently used to. Multicellular aging is a collection of random side effects that vary between species - there are many animal species that are effectively immortal.