Old Testament scriptures which do not directly preach a trinitarian Godhead still carry hints of the Christian conception of God, such as God playing multiple roles in a single situation, and we Christians should not be foolish enough to say that God can’t be even more than a three-personal God. What we can say is that God is not less than a three-personal God.
We can only say what he is to the extent he has revealed himself and he’s revealed himself as one and three.