Evidence

[MindForgedManacle]

What is it about our evolution as humans (I don't have a problem with the theory of evolution) that we can even ask the question "why."

I think the answer offered by evolutionary psychologists seems apt. It essentially boils down to our evolutionary ingrained disposition towards associating agency behind things, which at times is a false positive, but has no negative impact with regards to reproduction. The usual analogy is that of a pre-human species who sees/hears the grass rustle. If they think it's a tiger in the grass and run away even though it was just the grass, they've had a false positive.

Is there a difference between "why do the stars move that way" and "how do the stars move that way." Aren't scientists moved to investigate by asking why, not just how?

There's a difference. Asking 'why' the stars move the way they do is fundamentally unanswerable, because there's no logically necessary reason why things behave the way they do at all (see David Hume's Adam and billiards analogy). That things behave as they do doesn't seem amenable to any necessity and can be infinitely be pushed back.

I don't think science (in a case like this) deals in 'whys'.