I think many are looking at it the wrong way.
If you think you are no more than matter(your body) than you are not immortal.
But when you find the energy part of you, which in reality is you, you are immortal and can then go on to meet those who have long left this 3rd plane and are out there in another plane of the universe.
Everybody agrees we are all star stuff, but forgets star stuff is not just matter, it is a constant changing of energy to matter and back.

(ok, I considder myself more than just a lump of matter.
The difference between life and dead matter is,
that life actively counters a gain in Entrophy by
using metabolism. Dead matter does not, at least not
by some purpose.)

Anyhow. In Evolution species evolve by adaption to an environment.
If the environment is very very static, and there are almost
no natural predetor, a species can optimize to live
an almost immortal life -> at the cost of having to have
a very simple organic structure.

Such is the case with fungi and sponges.

But mammals dont live in such an environment. Also their
bodystructure is much more complex and fragile.
Immortality would come at an energetic cost
that would make the mammal have a hard time to compete against
fast-generation populations.

As I said, long living self repairing tissue is very energy intensive,
and likely to operate very slow (metatobic rate) and
be clunky due to needed heavy protection against environmental factors.
(Giant Turtles went into that niche)

Such a species is not very fit against its short living competitors.
-> who can develop fast growing, powerful organs,
that dont need to be build to last very long.
(Like a Formula 1 car vs a Diesel Traktor)

I only wanted to ask, why do people need IMMORTALITY? I just wanted to know... To leave forever? What for?

people want to live forever cause of fear of the unknown Is there live after death ?

For me, it's just the same as if children afraid of darkness.. We just need to grow up from that.. As for me, I think that there is nothing to be afraid of, sooner or later, we all will be there, but for now, we have to make something, that we could leave after we will be gone. Just my two cents.

If you fear the unknown, killing yourself would be the solution to that problem. People rather want to live longer because they are curious how the world will look like in 1000 years from now.

we are immortals from the point of view of very simple organisms having a really short life period, but we are nothing comparing to our galasy. so immortality is easily achievable by finding just the proper reference

Agreed. looking at the last 150 years and the exponential growth contained within, I can only attempt to imagine what could be if we restrain from destroying ourselves in 1000 years.

well i am not that curious about the future in 1000 years
simply by knowing we all get born and we all know for sure we die

ps if you fear what comes after death than its not logical to kill yourself right unless you get a kick out of fear

Yes, but it would be logical when you fear death because it's unknown.

Anyway, normally no one fears death. Death is far away. But anyone fears death when immediately confronted with it. In that situation you normally don't contemplate what comes after death. You instinctively know that it's the end, and that's what you fear.