Alright, well you've given me a laugh, because you're basically asking me to tell you what the meaning of life is. :) And I'm probably arrogant enough to think I have something interesting to say on the matter, so I'll try to answer your question. Hopefully I can be concise, but let's see.
There are two different persectives on the world that I see people grappling with regularly. Let's 'characturize' them as "Heads" and "Tails" to remove any preconditioned linguistic biases:
"Heads" is the perspective of a mind which holds a model of the world in which they imagine that they can fast-forward through time and fly through space. They look at the world and say "I've extrapolated outward. I've imagined what will happen to my body when I die, and what will happen to the world when it dies, and to the sun when it dies, etc. And I see that being a scattering of unobserved molecules in the tiniest region of space for a mere instant is not much of anything. Life, as far as I can tell, is objectively meaningless."
For some people, this realization leads to confusion, if not outright existential crisis. But we can look at it and wonder why it has any credence? What's wrong with it?
1. You can't actually fly through space and time. You're extrapolating, and even if those extrapolations are true, they do not stop being extrapolations. (Some take this "who really knows?" hopeful thought and pronounce the invalidity of exptrapolation instead. I think this is shallow, but it does evade the crisis.)
2. No meaning is "objective". Life isn't objective, and it can't be "objectively" meaningless. It's subjectively meaningful, and who cares about objectivity anyway?
Point 2 can lead us to the "Tails" perspective: "I've looked at the world and seen hypocrisy and the relativism of meaning. I've imagined what is good and been told it is bad and that what is bad is good. There is no good or bad, only winners and losers. History is written by the victors. Life is meaningful, but it doesn't have the same meaning for everyone. And your meaning means nothing to me."
Both of these perspectives are self-contradictory in the same way: they fail to reconcile the objectivity of reality with the subjectivity of experience.
Heads declares that life is objectively meaningless, and procedes to improperly internalize this realization: Heads is not an objective being, so why would they think they can hold objective meanings in their head? They can't! Heads subjectively experiences the meaningless life, but declares it to be an objective truth.
Tails declares that reality itself is subjective, because all meaning is subjective. But they have trouble accounting for the selection processes -- if history is written by the victor, who chooses the victor? Victors can't choose themselves, or we'd all be victors. They can't be destined or selected by a higher being or purpose, because that would imply an objective reality.
So what's the deal? Meaning is always subjective and meaningful. "Bare" reality is always objective and meaningless. "True" reality is both at once, and we can look at things as being comprised of either as we wish. I can look at you and see a pile of pointless molecules, or I can look at you and see an intricate reflective signal which communicates something significant only to me. I know I can do these things, regardless of what the implications of that are (which I won't speak to.)
Why should you care about future people? Future people are just an extrapolation in your brain. They don't actually exist, so what good is valuing them? Well... you're a future person. Or you once were. (But that's as much an extrapolation.) But what are you now? Still nothing but an extrapolation. Your identity is a mental model. You have to decide why you care about one extrapolation over another. Why does one ghost matter more than another?
Personally, the ghosts that are realist to me are the ones that we both see. And I see future people, and I hope you see them too. And I hope you want to be one of them as much as I do.