A valid concept is a valid concept no matter what era it comes from or who proposes it. A good idea is a good idea no matter where it comes from.
To discount valid concepts and good ideas from people in other eras and times just because they practiced some things that we now believe to be wrong is just as prejudiced and...well...stupid....as discounting everything somebody says now just because they don't get everything right.
That's why we don't read our 21st century morality into our moral judgment of people of another time. To do so can even make us hypocrites because who among us can say with certainty that we wouldn't be the same as they were if we lived in their time?
But yes, I believe there are universal truths that have been recognized in all times. They don't change just because the people change culturally or morally.
That there is a yearning within all people for personal freedom I believe is a universal truth.