primary vs 1st

primary is a noun but 1st is not a noun.

Word	Noun	Adjective	Verb	Adverb
primary	Yes	Yes	No	No
1st	No	Yes	No	No

primary (noun)	1st (noun)
a preliminary election where delegates or nominees are chosen
one of the main flight feathers projecting along the outer edge of a bird's wing
coil forming the part of an electrical circuit such that changing current in it induces a current in a neighboring circuit
(astronomy) a celestial body (especially a star) relative to other objects in orbit around it

primary (adjective)	1st (adjective)
of first rank or importance or value; direct and immediate rather than secondary	preceding all others in time or space or degree
of or being the essential or basic part
most important element
not derived from or reducible to something else; basic