I would suggest looking into the alien-contact psychological essays of exobiology.
Tashah, the most educated sage of exobiology is still speculating about something he's never seen. Educated speculation, perhaps, but speculation nonetheless.
The whole planet-search, which is a recent phenomenon, has blown many theories about how solar systems form right out of the cosmos. Astrophysicists were stunned to find giant Jovian planets orbiting their stars at radii less than Mercury's orbit; it was considered impossible. Other results have been totally opposite what we expected...many systems do not seem to follow the same "rules" as ours in terms of orbits, planet types, etc.
See, we were
speculating about other solar systems, but until the past 15 years we'd never
seen one. A lot of our speculation turned out flat wrong.
I think that with aliens it may well be the same. Speculation can be useful, as it can propose many thought-models, some of which might be in the ballpark...but it isn't
knowing.
Two centuries ago, the idea that we would be able not only to split the atom, but to harness its power within a concrete building and produce energy with it, was virtually inconcievable to the
educated public. Men flying by mechanical means was a belly-laugh to most people. We had not yet harnessed electricity. To a person of the year 1809, the technologies we take for granted today would seem almost miraculous.
Yet, our society and our human nature has not changed nearly as dramatically. We still make war; some societies still enslave; individuals still commit crimes against others. A person of 1809 would certainly be surprised at some aspect of our social order, but would soon recognize that human nature itself has not significantly changed.
In theory, aliens might have a civilization a billion years old; those who believe this tend to all but deify aliens and assume they are beyond our comprehension but benevolent. However, some scientists doubt that any civilization can endure so long without collapsing back into barbarism, probably several times in cycles of rising and falling. Our own planet has seen this several times, the most dramatic example being Rome and the Dark Ages that followed its collapse.
If we can go from horse-and-buggy to nuclear power and space shuttles in 200 years, can we be so certain that another 200 years will not see us developing a means of crossing the stars? Right now most existing theories say no...but 200 years ago there was no theory of nuclear power either. Yet in 200 years, do you think human nature will change significantly? I don't. There's little evidence of it.
Aliens could be no more socially or psychologically advanced than we are, and only moderately higher in technology. The assumption that they would be peaceful, benevolent demi-gods is merely speculation with no basis in fact. It isn't even certain that their homewold would have a singular government, or that they would have ceased warring on
each other.
Interstellar travel could be only one Einsteinian-level "Eureka!" away. Or it might be forever impractical...we don't
know.