The article in question is found here (might be behind some paywall depending on browser cookies, and unfortunately in german):
https://www.nzz.ch/meinung/sklaven-von-natur-ueber-die-entstehung-des-hautfarbenrassismus-ld.1601853
As it is written in german language, I try to distill some of the most important points:
There are some points in the article that make me sceptical; first it a Bernard Lewis is mentioned who allegedly proved this in 1971. Googling after this person revealed some questionable background. Furthermore, some vocabulary in the article go into the direction of being politically motivated; especially against the current left-wing opinions on race in the USA.
As the NZZ is a usually internationally respected serious publication, surely conservative but definitely no extreme alt-right paper, I'd like to ask the historians here how credible the claims in this article really are.
First off, let me say that making racial or ethnic distinctions in order to figure out who is "out" and who is "in" seems to be a human constant.
For many years I taught my students that "race" based on skin color was a distinction that arose only with African slavery in the 1500s and 1600s. The scholarship, however, quickly changed as historians began looking more closely at the ways in which people in the past made up the categories that they wanted to use.
From my experience teaching Islam, I would argue that the biggest distinction that thinkers in the early Islamic world used was language: speaking Arabic as opposed to Persian, for example, could prove you were an "Arab." Adopting Arab dress and learning to speak Arabic were two things that converts to Islam used to "Arab-ize" themselves. This was probably also true in the western European Middle Ages, in which your native language was connected to your ethnicity.
Geraldine Heng has recently written a book (The Invention of Race in the European Middle Ages, Cambridge 2018) in which she argues that in the European context, race was invented and made a shorthand proxy for virtue and vice: white/virtuous/good v. black/unvirtuous/bad. The argument is convincing to me, and worth a look.
In re Bernard Lewis, he was arguably the most important American scholar on the Middle East in the 20th century. His work became very political after Sept. 11, 2001 and was used to justify modern political actions based on his understanding of "What went wrong?" in Islam. Not surprisingly, there were many scholars who took exception to that question.