Anspruchslosigkeit:
"-igkeit" is the standard substantivated adjective ending, the origin is the adjective: "anspruchslos", which in itself is a derivation of the substantive "Anspruch" with the suffix "-los" to express a non-existantness (that was by far my worst adjective ever..)
"Anspruch" means something like "entitlement"
Einfachheit:
"-heit" also is one of the standard substantivated adjective endings.
The other word component here is: "einfach" which means "simple", "easy".
Best translation for this word would probably be "simpleness."
This is probably the word you are looking for in a general context
Schmucklosigkeit:
Here again we see the the standard ending "-igkeit". The original adjective is also a combination of a Substantive and the suffix "-los" (as explained above).
"Schmuck" is "ornaments" here and thus "schmucklos" means "plain", "non-ornamental" or "functional".
Ursprünglichkeit:
Very similar to "-heit" (and probably ethymologically related), the suffix "-keit" again denotes the substantivation of an adjective, in this case "ursprünglich".
this word again comes from "Ursprung" which means "origin" or somtimes "cause". The in my opinion most fitting translation would be: "naturality" or "originality".