Based on your comment, you will likely enjoy "The Boat of a Million Years", by Poul Anderson [0]. Needless to say, it's science fiction. It's about a very smal

Based on your comment, you will likely enjoy "The Boat of a Million Years", by Poul Anderson [0]. Needless to say, it's science fiction. It's about a very small number of people who are immortal, in the sense they stop ageing at 25 (iirc). They can be killed like anyone else, but smaller damages do heal faster. Also, they never get sick. Some are thousands of years old, some less. Some smart, some not so much. How they handle their immortality is very interesting though. I won't spoil it for you though. [0]: https://en.wikipedia.org/wiki/The_Boat_of_a_Million_Years https://en.wikipedia.org/wiki/The_Boat_of_a_Million_Years