I guess that's fair. Americans see it as their role to prevent other people from their recurrent Holocausts. You leave Europe alone for a century and a genocide will ensue. Leave Europe alone for a decade and a war will ensue. Leave Europe alone for a year and violence will ensue. I suppose one could let that happen. But it's hard to say that the extinction of some racial group is a generally acceptable thing.
Irrespective of the origins of America, that is a categorical difference in the scale of death and destruction. To Americans, that is barbarism, but it's possible that Europeans do not see it as such and perhaps see civilization as inherently violent.
They are foreign to us here and speak different languages so perhaps their true minds are forever opaque to us, but we can see their actions: and that is repetitive quarrels with their neighbours with frequent attempts at ethnic extinction. From that, some conclusions can be drawn.