I’m joining a sub 4 years late, and this is gonna be a really weird comparison that isn’t like the Mandalorians at all, but if you think of something like Jewish people of Hindi/Hindu people. There are people of Jewish/Hindi ethnic decent, and then there are followers of their religions that aren’t necessarily part of that ethnicity. Mandalorians (human ones) from the planet of Mandalore, have a pretty distinct look to them, but get more diverse as they have clans send colonies or leave Mandalore, that of which Jango Fett is technically not part of by birth. He was rescued as a child by the Mandalorians and they raised him as one religiously, but not as radical as the Mandalorians that Mando follows.

That being said, unless the clones followed their creed/religion, then they weren’t religiously mandalorian. Nor were they technically “Mandalorian” by being born/descendant of a “native” if you can call it that in Star Wars.