The verse in question is Genesis 1:26, which says: “And God said, Let us make man in our image, after our likeness: and let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth.”
A very interesting question, Elana. What you are beholding here is a case and point example of the Trinity! Consider a similar phraseology from Isaiah 6:8. Isaiah is in the throne room of God listening to God commune with Himself:
“Also I heard the voice of the Lord, saying, Whom shall I send, and who will go for us? Then said I, Here am I; send me.”
Isaiah is hearing God talking with Himself—Father, Son, and Holy Spirit conversing with one another.
Like you said, God could not be talking to angels as they did not exist yet—or at the very least there is no Scriptural data in Genesis to indicate that they existed yet. Even if they did, it wouldn’t matter as Scripture says we’re made in God’s image (Genesis 1:27). Therefore it would make no sense for God and an angel to say “we’re going to make man in our image”. No living being (specifically in the sense of a living soul, see Genesis 2:7) existed yet except the Life-Giver of Yaweh Himself. Therefore, “Us” and “Our” in Genesis 1:26 record God talking betwixt Himself. This shows God’s wonderful triune nature.
Thanks for the question!
God bless,
Robert A. Rowlett