Earlier quoted context omitted.
But I don't understand how the question "what is the purpose of X" can be anything but philosophical. Science is primarily concerned with creating models of reality and testing the predictive power of those models. The "purpose" of something is not really a meaningful concept in that context. ... unless by "purpose" you mean cause? As in, what caused our universe to exist? That is also not really a meaningful questio…
> But I don't understand how the question "what is the purpose of X" can be anything but philosophical. Again, my guess is that this depends on how much we know. Or, there about has to be a purpose. And eventually as we learn more there should be some clues about what that purpose is. So I'm wondering if we know that much yet? A first little clue is the speed of light speed limit that so far seems to say that we are…
Why does there have to be a purpose? The rest of your post is discussing philosophy, but I'll indulge anyway.
> A first little clue is the speed of light speed limit that so far seems to say that we are quite isolated from the rest of the universe. So, somehow having us isolated was deliberate.
What makes you think it was deliberate? The derivation of the speed of light comes directly from Maxwell's equations (which just describe how electric and magnetic fields interact).
Relativity further extends that idea by "simply" noticing that the propagation of light can only work if the waves travel at the speed of light relative to the observer. Thus all light must be travelling at the same speed no matter the speed of the observer, which gives you the entirety of special relativity (that predicts that no information can propagate faster than the speed of light).
I'm not sure which part of the above you could claim is deliberate. We live in a local universe (it takes time for information to travel) and thus light must have a speed. It doesn't actually matter what the speed of light is, the same derivation would apply as long as the speed is finite. Are you saying that the fact that our universe is local is deliberate?
> Then there's the 3 K background radiation. That's one heck of a clue. What might be the reason for giving us such data?
What makes you think it's data? It's literally just the echo of the big bang and comes from the random thermal motion in the "early days" of the big bang. The reason it's 3K is that it has been cooling since the big bang and that's the temperature it happens to be today. If it were any other temperature, would that also be a clue?
> There's the Heisenberg uncertainty principle. [...] We are stopped at that level by some dice rolling.
Quantum mechanics isn't dice rolling. It is true that there cannot be a local hidden-variables theory of QM, but QM still has incredible predictive power when discussing the probabilities of experiments. It is possible in the future that a non-probabilistic view of QM will emerge, it just cannot be both hidden-variables and local.
> So, what the heck is the purpose of us being here, our existing? That is, we're the most special and amazing thing we know of in the universe.
If ants could think, they would probably think they're the most amazing thing they know of in the universe. The only reason we think we're so amazing is because we have no competitor to compare to.
> Or, if there is no purpose, then this is one heck of a big show for nothing!
I don't think that life has an intrinsic purpose. In particular, it personally feels very selfish to claim that my existence is somehow meaningful to something as enormous as the universe. It just feels like unjustified hubris.