It is quite extensive and complete the information you collected about people and cultures that talk about eternal life.
Beyond being biologically unviable, philosophically we think: Are we really prepared and willing to live eternally?
suppose we do not get sick, that we can not break our bones, life would completely lose its meaning, it would become monotonous and boring.
Imagine seeing a movie that never ends, eating a meal that never ends or a book without end, the joke of all is to come to an end and enjoy the trip.
take each experience and live it, leave the fears and fulfill every idea you can, enjoy the maximum possible because we will inevitably die.
RE: The History of Immortality: Searching for Eternal Life, Part I: Ancient World