Considering Western world slavery, and thus American slavery, began not with the UK, but with Portugal, I fail to see how America got it's racism from 'the mother country', when this country was a mix of Portuguese, Spanish, French and British colonialism and slavery. Not one African slave set foot IN Europe to become slaves. Ergo, the racist mindset colonists adopted didn't come 'from' anything but themselves.

The only thing you have correct is that colourism exists all over. But what colourism in one country, can be seen as racism by others. And vice versa.