Do me a favor...open your Bible (you have one, right?) and read the first few verses of the first chapter of each of those books. They ALL start out identifying Paul, himself, as the writer. As to your "generally regarded" statement, I'd have to ask, by whom?, as it really is generally regarded as Paul being the author since he identifies himself at the start. Whether or not an associate of Paul maybe being the secretary writing down what Paul says, is a possibility, but the autograph IS from Paul...every one. Another point is that the early churches would have known what letters they got and from whom they came as the Apostles had emissaries as well as personally delivering some of the epistles. From the start, the Christians knew and accepted the authority of the Apostles and received their writings AS Scripture. Any suggestion that an author was unknown is preposterous as the believers would NOT have received letters from anonymous writers. Didn't happen.
Whoever wrote Ephesians, Colossians, 1& 2 Thessalonians, Philemon, 1 & 2 Timothy, and Titus wanted the readers, bothin his own time and afterwards, to think that Paul had written them. If I write something and identify myself as Shakespeare, are you going to tell me just to read the part where Shakespeare is identified as the author?
There is a large number of scholars who regard 1 & 2 Timothy and Titus as pseudepigraphical works.
As I noted, we do not have originals, and the later Christians did not know any of the Apostles. Signing one of their names would give a work more authority. And most people couldn’t read, so if the priests and the scribes said this is from Paul, or Matthew, or John, they accepted it. It got handed down, and it got attributed to Paul, in some cases accurately, in some cases probably not.
You seem to be arguing from a predetermined conclusion and anything that contradicts or questions that predetermined conclusion, it seems, must be invalid, in your view, simply because it disagrees.