Let me offer some interesting questions for you to ponder further!
1. Factual Relativism: This is without a doubt the most fundamental philosophy of my psyche and has been for something like 6 or 7 years. The basic idea is this. The basic idea of Factual relativism is that the universe is only interpreted by observers and all observers have bias. Suppose you have some truth, in order to interpret this truth you need to observe the truth and in observing the truth you automatically apply a bias towards it, which augments the truth to you. Now here "Bias" is general as it can get as is observer, an observer is not necessarily a conscious being but could be any theoretical point in the universe, and a bias is not a conscious thing but could also be physical, limited by the information you can see and your location in the universe (For example, the fact you can't see the stars in the day I would consider a "Bias" cause you're on earth inside the atmosphere). We call the world interpreted by some observer a "Reference frame" (I've extended this philosophy to include a world interpreted by more than one observers, something I call a "Reference Set").
Now, because one needs to observe a truth in order to interpret the truth, and by interpreting the truth you apply a bias which augments that truth in your reference frame, the fundamental thing occurs. It is impossible to absolutely prove anything about our universe, IE: We can never know a real "Truth". So I suppose that means we should simply give up right? If nothing can be known than what's the point of trying to know. Well, while nothing can be known with certainty, it is possible for you to know something in your own reference frame and it is possible for a group of people to know something within that groups reference frame. So instead of asking "What is true?" perhaps you should ask "What is true for me?" or "What is true for the world?". This is my philosophy of set relativism, instigating that different groups of people can have different truths, and sometimes they're the only meaningful ones.
So you say you're going to die and it's not gonna matter in the world, well for one, as I said before you're instigating a universal truth, that your death doesn't matter, but you can't prove this. This entire universe may simply be in your imagination, or there may be a god who designed this universe especially for you. While this things are unlikely they're not impossible, so you can't actually prove that you don't matter to the universe. But something that you can absolutely prove, is that you matter to you. You can't prove universal truths but you can prove truths in your own reference frame, and a truth (I hope) in your own reference frame is that YOU matter to you. Now, while you can never prove this, you can definitely infer it, but you probably matter to your friends reference frames. You probably matter to your family's reference frames. It is a truth for your friends and your family that you, absolutely, matter and because we can never know any universal truths, aren't these truths the only ones that really matter?
Basically my point is there's literally no point wondering whether or not you the you matter to the world. It's knowledge we will never ever know, so instead of trying to think about that knowledge, think about the knowledge you can find out. Do you matter to your friends? Do you matter to your family? Do you matter to you? Instead of trying to make an impact in the universe, try to make an impact in the world, because whether or not your life has meaning in the grand scheme of things, it almost definitely has meaning on the small scale. We can NEVER know the truth on the grand scale, we can ONLY know the truth on the small scale, so really, the small scale is the only scale that matters.
As for whether or not we have freewill, there is an inherent uncertainty within the universe within Quantum mechanics based on our current understanding. This uncertainty within the fundamental world around us could give us uncertainty in our actions, for example our brains might utilize quantum mechanics such that our thoughts are fundamentally non-deterministic. This would mean that there would be leeway for a universe where you're not always set on a path, but instead this might be a universe where your path cannot be determined, as your thoughts cannot be determined because the world cannot be determined.
