Getting old

Hello community, I have been thinking about age, and I thought that aging is the reverse of how a biological system is able to fix itself over time. Actually, some species actually are able to reverse it completely, such as the jellyfish and lobsters for up to 400 years in the Greenland sharks. Moreover, by evolution principle, those species must've exchanged this ability over others, which is noticeable considering they're really adapted to their habitats.

What does research tell us on aging so far?

According to Britannica, aging affects many dimensions for all humans.

So, when scientists are talking about "a cure to aging", I cannot comprehend whether they're proving that those are symptoms of some biological factor (such as producing a certain gene, etc.) or whether all of them share the likelihood to appear more often over a certain age?

How can studying those species help science advance in research?