People are more alike than not? Well yes. And no.
Yes we all have the basics of being human. We all see the world with the same senses. We all feel the same feelings. Anger is easy to spot in a person no matter the language. Happiness, sadness, etc. We all want what is best for our families. We all want to be allowed to live in peace and have a fair chance at improving our lot in life.
No, because 'how' we define those ideals can be different from culture to culture, and even region to region within the same culture. How we experience those ideals in our lives change us just as much. You and I live in an environment that is essentially safe, reasonably comfortable, and in societies that leaves us to pretty much do as we please (within the confines of our mutual acceptable values). These refugees have had little to none of any of that. And they how they act towards the world is very different because of that. They are afraid, angry, bitter, suspicious. Through no fault of their own; rather because they have had to be just to survive.
Real world examples. They are everywhere. Here is a very simple example. In the U.S. the gulf between Black culture and White culture is immense. To the extent that there is little overlap between the two. I live in an area which is reasonably split between Whites, Blacks and Hispanics. I am friendly towards all of them, and they are all friendly with me. I have few actual friends from those other cultures though. I have only a couple Black friends. People I am close to and spend time with. And that is uncommon. Most Whites do not have any Black friends. There's nothing nefarious about that; people tend to group with those they are comfortable with. And they are comfortable with people who think like they do.
What preparations should have been made? An awareness of everything I just said would have been a good place to start. To expect that these refugees would be so thrilled to escape to a safe haven that they would immediately adjust their life views to the ideals of Western Culture is absurd. Yet that is what Westerners seem to believe should have happened.