original vs 1st

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

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

original (noun)	1st (noun)
an original creation (i.e., an audio recording) from which copies can be made
something that serves as a model or a basis for making copies

original (adjective)	1st (adjective)
being or productive of something fresh and unusual; or being as first made or thought of	preceding all others in time or space or degree
(of e.g. information) not secondhand or by way of something intermediary
not derived or copied or translated from something else
preceding all others in time or being as first made or performed