Its not debatable if you really have studied a NT. and are this......."Pauline Theology", as am I.
Here is how you know that Paul wrote Hebrews..
3 Things..
1. In the last chapter, He talks about Timothy, and Timothy was Paul's convert.
2. Hebrews 8-13, are all doctrine, that explain the Blood Atonement, and that is Paul's Gospel.
3. Hebrews 10:26, is Paul preaching to Unsaved Hebrew Christ Rejectors. So, if you then go to Acts 28, the last 10 verses, you'll find Paul doing it AGAIN, and this could be the same situation...
Take 5 mins and open your NT.
If you know Paul, as Romans and Colossians, and Ephesians.....if you KNOW Him, deeply, having studied say......Romans 3:21-28, then you'll recognize Him, whenever He teaches as he is very specific to the Blood Atonement as Salvation.
And that is just one way you can know that Hebrews is Paul's letter.