Interesting how people (including producers, directors, casting directors, etc) envision fiction characters differently. As a reader, I always assumed the Dune universe to be about as diverse as the real world.
Atreides were Italian-ish because they were descended from the Romans and I pictured Caladan something like Malian or Tuscany with mountains, rivers and agriculture. Eagle crest, etc.
Fremen were Arabic because of the customs and language used (hospitable people, religious, used arabic like words, lived in the desert, etc).
Sardaukar were Japanese because of the similarities to Samurai (swordsmanship, knives, darts, etc).
Baron Vladimir Harkonnen was Slavic to me since the name Vladimir is rarely used outside of Slavic families.
I originally envisioned Shaddam Corrino as Middle Eastern because the names looked like Saddam and sounds Jewish, but later changed it to more French when Herbert described him as as having sharp features dominated by cold eyes and the descriptions of his daughters and their names being sorta French sounding, etc. (I think this was intended to be a Jewish stereotype but I missed it)
The Bene Gesserit were interracial since breeding for genetics was more important than keeping a house lineage together. I mostly saw them as sorta like Latino and Catholic.
Ixians were Chinese since they made everything.
Duncan Idaho was Native American - no idea why I saw that even when he was described as being more Anglo - perhaps Idaho is Native American land in my mind.
Harkonnen were basically like space vikings since they shared a similar tortuous way (e.g. blood eagle). Nordic people all the way.
Tleilaxu were sorta amorphic to me - like odd looking Santa elves.
People of African decent were just kinda mixed into the crowd in my mind (like some of the smugglers, part of crowd of Alia worshippers, etc), but I never saw a prominent group being distinctly described in Hubert’s books as African. Such is the all to often fate of Africans in science fiction I guess…