Let's define immortality. If someone offered me some fountain of youth juice that extended my life by 10,000 years. Hell's to the yes, that'd be mad bomb. If instead my lucidity and ego were forced to persist for a literal infinite amount of time, that would be a horror of the grandest scale. Come on? Really? An eternity? No. Good Lord, no. We're human, our minds are not arranged to endure such a thing. For a person (an ego) to face an eternity they'd have to completely reconfigure their consciousness, effectively killing their former self.
So (hopefully), the immortality we're talking about, is essentially an extended lease. This flavor:
https://imgur.com/gallery/HjF2P.
That kind of immortality is totally possible, and sign me up! However, death remains the ultimate fate. Absolute annihilation, one day. An extension on life does not changed my feelings towards it.
There is nothing wrong with the world (all things that exist). Nothing at all. The world is not for any reason, and it does not do anything. It just is. Usefulness, purpose, outcome. These are human concepts, not attributes of our world. Value, truth, passion, compassion, justice, beauty. These are human concepts, not attributes of our world.
Our world has a boundary. Spacetime. Nothing can exist before, or after, or outside.
We're here, and here is going to end. All things fade, and are forgotten. All information, gone. It didn't even happen. And nothing will change that.
It's up to each one of us, to deal with that. This is your postmodern attitude. Like the world is ending, because it does. Accept and find peace / Revolt and fight for every last breath / believe the comforting lies about inherent significance in life. Doesn't matter, all actions are equivalent in their non-value.
Now you don't have to believe that. What evidence do I have to make such a board claim about the nature of things?
The world is very much a mystery. Without being able to prove or disprove or assign probability to any model of reality, they are all equal. It's a canvas. This is free will.
Free will is not that a person can do whatever they want without limitation, as people are limited by the capacity of their mind and by the natural laws.
What free will is, is that the world offers no clues as to what the "proper" course of action and perception is. Our path, our reality, is of our own making in that way.
If you despair at your fate. That's you doing that, that's who you are, that's what you want. You want to use death as a scapegoat, you use it as a punching bag for your misplaced frustration. You're not upset at death. You're upset that you find no value or purpose in your life and you blame death. You blame death for the fact that you can't seem to care enough to do anything about injustice, or an unfavorable future, or that you don't have the balls to face a challenge that will destroy you.
But if you find significance in your actions, there will be, you have the freedom to create and assign it. It exists in you doesn't it? So it's real. The whole universe exists in you. Everything you know, everything you've experienced or will every experience is a product of your mind. You have influence in this domain.
You have free will. You can paint a better reality. Cultivate a world of you ideals. Death is not an obstacle. You are.
It just you. Your choices. Your beliefs.
But this is very difficult, because you have to purge yourself of the infectious thoughts that plague you. You have to craft your assumptions about reality (and they are that) into ones that serve you.
Don't fear death. Embrace life, in all it's horrors and wonders. I wish I could take my own advice.