Where does “Ἀνδρέας” come from?

Ἀνδρέας (Ancient Greek) comes from Ancient Greek ἀνήρ, from Proto-Hellenic *anḗr.

Ancestry of “Ἀνδρέας”, step by step

Step	Language	Word	Meaning
1	Ancient Greek	ἀνήρ	man; husband; human being, as opposed to a god
2	Proto-Hellenic	*anḗr	—

Ἀνδρέας — Etymology, Origin & Word History | Etymology Explorer