“Othering” is, apparently, a core human behaviour. Dividing people into in-group and out-group and then proceeding to verbally increase the separation as much as they can. Humans are really not far from relatively isolating tribal groups of less than Dunbar’s limit size. Essentially they can only really know a small group, can only trust who they know, and try to keep safe from untrustworthy humans by clearly marking them as outsiders every chance they get.

We just happen to strike them as fundamentally different immediately and that makes it easy to consider us “other”, so we jump to the top of the list.