As to whether or not cryptos will divide humanity is a loaded question. People will be divided no matter what, at least for the nonce. The whole aim of the blockchain is to decentralize the monetary system and if and when that happens then other things will follow.

Division and separation comes from lack and limitation and the concentration of power. We know that the ruling class tends to employ the divide and conquer strategy to ensure they remain in control. But if the blockchain takes power from them, then it is not possible for them to do these things.

That said, one has to take into consideration other things such as culture and all the stuff that tends to balkanize people. Will the blockchain exacerbate these difference? Or will it help to pull people together? I doubt. But who know.