You are correct to say that Paul never says Jesus of Nazareth. But what does he say? He uses the term Jesus 206 times. He speaks about his crucifixion in 1 Corinthians 1-2, which clearly is a reference to an earthly Jesus. He notes that he took on humanity in Philippians 2:5-11, which also is an indication of his life on earth. He discusses whether he taught on a given topic (the abandonment of a spouse) in 1 Corinthians 7. In Galatians 4:4-5 he discusses when he was born. Your remarks fall into a common category where a topic is viewed as mentioned or not because particular terms are or are not present. There is no doubt Paul is discussing Jesus of Nazareth. I have not even mentioned the reports of Paul's vision that Acts presents as from him (which I am sure you would say Luke made up) even though it is a nice corroboration of what Paul says about his experience in Galatians 1. This Acts event the Acts Seminar (an extension of the Jesus Seminar and hardly a conservative group) rated as a quite likely historical event. When your remark forces a choice between a cosmic figure and a man it ignores the very combination he depicts in Philippians 2 or Galatians 4:4-5. Part of what allows a gospel message to come from Paul is that Jesus represents humanity in part because he is a real human person. By the way, none of this nullifies the key point was being made, which was that the dating of these ideas from Paul. We are still in the mid-thirties for these thoughts, given Paul's experience of seeing the risen Jesus, an experience that so impacted him that he speaks of Jesus as he now is-- raised and exalted. Thus Paul has many references to Jesus Christ or the Lord Jesus Christ.