early 15c., primarie, "earliest, most basic, first in time or sequence;" 1560s, "first or highest in rank or importance," from Latin primarius "of the first rank, chief, principal, excellent," from primus "first" (see prime (adj.)).
The meaning "first or lowest in order of growth or development; elementary, preparatory" is from c. 1800, first in education; primary school is attested by 1793 in translations from French, from école primaire.
The Paris journals ... are full of a plan, brought forward by Fourcroy, for the establishment of primary schools, which is not interesting to an English reader. [London Times, April 27, 1802]
Primary color is attested from 1610s (at first the seven of the spectrum, later the three pigments from which the others can be made). Related: Primarily.
Primary and prime mean first in time, and now especially first in order of importance: as, a primary class, definition, consideration, planet; prime mover, importance, idea .... Primitive means belonging to the beginning or origin, original, hence old-fashioned, having an old-fashioned simplicity: as, a primitive word, the primitive church, primitive purity, manners, unconventionality, dress. ... Primeval means of the flrst or earliest ages, and nothing else. [Century Dictionary]