precursor vs doer

precursor and doer both are nouns.

Word	Noun	Adjective	Verb	Adverb
precursor	Yes	No	No	No
doer	Yes	No	No	No

As nouns, doer is a hypernym of precursor; that is, doer is a word with a broader meaning than precursor:

Other hypernyms of precursor include actor, worker.

precursor (noun)	doer (noun)
something that precedes and indicates the approach of something or someone	a person who acts and gets things done
a person who goes before or announces the coming of another
a substance from which another substance is formed (especially by a metabolic reaction)