1st vs original

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

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

1st (noun)	original (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

1st (adjective)	original (adjective)
preceding all others in time or space or degree	being or productive of something fresh and unusual; or being as first made or thought of
	(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