There is no physical/chemical/biological reason you can’t live indefinitely with the health and vitality of a 25-35 year old. Aging isn’t a law of nature.
Odd then that every living thing ages and eventually dies?
but we haven't really even tried...
We have been trying since medicine existed. Granted we can see much further now thanks to modern knowledge and tools, but we still can't see far enough to identify the causes or even speculate about actual solutions to aging. For all our technology and medical knowledge, getting somebody to live past 100 is still 95% a mix of genetic lottery and the chance of not developing too serious of cancer until really late.