What I came up with was, “the help”. Lol. We’ll call that person the help. I guess if you have a really good chord progression but know melody and lyrics. You don’t have a song at all. You just have harmonies. But! You can receive a writers credit for coming up with chords I heard. I’ve made many productions where all I had was a synth pad instrument playing a chord progression and a synth bass playing the root notes from the chords, I had synthetic drums and some other sound effects, without a melody and lyric. And still received 50% writers credit for the background music I composed and produced. So I guess so.