late 14c., primitif, "of an original cause; of a thing from which something is derived; not secondary" (a sense now associated with primary), from Old French primitif "very first, original" (14c.) and directly from Latin primitivus "first or earliest of its kind," from primitus "at first," from primus "first" (see prime (adj.)).
Meaning "of or belonging to the first age" is from early 15c., especially in a Christian sense of "adhering to the qualities of the early Church." Meaning "having the style of an early or ancient time," especially "characterized by the (supposed) simplicity of the old times," is from 1680s.
In anthropology, of cultures that, through isolation, have remained at a simple level, by 1895. Of untrained modern artists from 1942 (earlier in reference to pre-Renaissance artists; 1847; also of art by "primitive" cultures or prehistoric ages). Related: Primitively.