"A galaxy is hundreds of millions of stars and planets. How can it be 'here'?"
It's not somewhere else.
Distance is relative. Compared to the far reaches, that is close.
We don't know what's out there. All we know is what the EM spectrum shows us. We know we're here. But as simultaneity breaks down from minutes, to days, to years, suddenly - we don't know. Perhaps to an external observer, the Milky Way is no more. It's confusing because what is, and what was, depends on physical energy which may be more or less fixed in its velocity under ideal conditions. If it is largely fixed, as Einstein insisted in order to derive his equations, then we know the past, but can't know what the present necessarily means.