forefather vs predecessor

forefather and predecessor both are nouns.

Word	Noun	Adjective	Verb	Adverb
forefather	Yes	No	No	No
predecessor	Yes	No	No	No

As nouns, predecessor is a hypernym of forefather; that is, predecessor is a word with a broader meaning than forefather:

forefather: person from an earlier time who contributed to the tradition shared by some group
predecessor: one who precedes you in time (as in holding a position or office)

forefather (noun)	predecessor (noun)
the founder of a family	something that precedes and indicates the approach of something or someone
person from an earlier time who contributed to the tradition shared by some group	one who precedes you in time (as in holding a position or office)