The biggest problem around the world in getting along with others is people tend to gravitate back to their primal instinct of belonging to a tribe. This urge causes backward progress, loss of individualism, prevents world harmony, and creates conflict.
The tribal society in its self, banishes those who look outside the tribe for friendship, companionship or self improvement. Hence advancement of all members stagnates and alienation grows.
Tribe against tribe, black against white, Muslim against Christian, Etc.