Angels do give us guidance, but they are mere helpers; the Lord alone governs us, through angels and spirits. Since angels have their assisting role, the words of this verse appear in the plural — "Let us make a human in our image." But since only the Lord rules and manages us, the next verse uses the singular — "God created the human in his image." (Secrets of Heaven 50)
'Let us go down,' as in Genesis 11:7, signifies the execution of judgment, which is done by spirits, specifically evil spirits.