I don’t think the human body in engineered for much more than 80-ish years.
Even if some diseases and issues associated with aging are resolved and/or mitigated in the next few decades, all that will do is push the frontier back a few years.
Think about a car - yes, the makers COULD build engines, or transmissions, or tires, or whatever, to a standard designed to last 50 years instead of 5-10, but even if one part was over-engineered, you’d have to over-engineer all of them for this to be effective. And over-engineering car parts is expensive.
Similarly, I think if the human body was over-engineered for longevity, there would be a cost factor (perhaps the body wouldn’t be as efficient - it would demand more energy per day or whatever).
In more human terms, this was driven home to me a couple of years ago. Yes, I sometimes had these thoughts myself (by the time I am 60, people will possibly routinely live to 100…) Then my eye doctor told me I have glaucoma. Untreated, it might cause blindness by age 60 or 70. So of course I started the treatment, and my follow-up was something like - “So, now my eyes will be good indefinitely, right?” Well, no, they would still degrade, but at a more normal rate - I shouldn’t have much to worry about for the next 50 years or so, though. But what if I want to live longer than 50 more years? If it ain’t the eyes, it’s gonna be something else.
Socrates was, AFAIK, in good physical and mental health when he was forced to take the hemlock at age 70 or so. St. Augustine lived to age 75 or 76 in the 5th century A.D. As distinguished citizens of what were, in their eras, the elite societies, they were aging about as well as could be expected. In the centuries since, medicine is much better, and our chance of dying of disease along the way (i.e. before age 60 or so), is much reduced, but the upper end of the lifespan hasn’t moved too much past those folks.