“Who authored the Psalms?”
Scripture clearly identifies many of the psalmists with superscriptions. Sometimes we even get a little bit of detail about the circumstances in which they wrote. For example, the superscription for Psalm 3 is “A Psalm of David, when he fled from Absalom his son”, and Psalm 7 is called “A Shiggaion of David, which he sang to the Lord concerning the words of Cush, a Benjaminite”.
Please don’t ask what a “shiggaion” is. It’s one of those words Strong’s Concordance labels as “doubtful”.