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.
Yes, it's a strange thought. At first, it would seem great to live forever, but would our minds tire of it?
In my opinion after a few centuries of life having explored every sensation, taste and smell until the satiety you would notice the absurdity of life and you would find it totally empty because you did everything you wanted.
Even to see the nature of the human I think it would make you despise them and get away from them because you would see their existence without meaning.