All right, time for you to get some knowledge handed to you OP
It just so happens that cultures aren't just fancy ways of attracting tourists and wooing females, but they're potent, rigid frameworks where values and taboos dictate behaviour.
That's a piece of Emmanuel Todd. He's a french historian/anthropologist, who has done research on family structure and marriage. He's noticed that some patterns do come out, and that those things vary a lot in different countries, or even regions.
Take France and USA. Historically, USA has always had a very low rate of exogamy (marrying outside of one's social/racial group), along the lines of 5%. For France, it's always been more like 30%, interracial marriages are far less of a shameful thing there.
Yet they're two countries that are very vocal about freedom, and they claim it as one of their founding values. But even though it's the same word, it entails entirely different meanings: Freedom of market in one case, and freedom from authority in another. And that kind of difference shows up in mating behaviour for example.
And it's the case for many different values in different countries. Basically, what's been cristallized through a constitution and laws is only a verbal continuation of silent and tacit rules that have been passed on for centuries.
There lies your problem. To claim an universal conception of human rights would imply that those silent rules are the same for everyone, and that people can accept only one definition of a given societal rule, such as equality or justice. But that's not the case, different countries exist because they hold their own values, which work the best for these people's biological imperatives (reproduction, wealth production, self-defense, etc).
It's also worth mentioning that human rights is a highly statist/nationalist creation. There are still some places where tribal law/family law take priority over it, and that's literally the opposite of 'universal'.