You are misinformed, ja4. this is NOT why they are called Deuterocanonical. It means “second canon”. It is a collection of Sacred Writings that is distinct from the other collections.
News flash, ja4. The Apostles and Prophets are also “but men”. It is not their humanity that made what they wrote inspired/inerrant, but the Spirit of God. It is that same Spirit that Jesus sent to “guide into all Truth”.
Because the Scriptures must be interpreted in the light of what those who wrote them believed. When this does not happen, all kinds of misinterpretations occur. For example, Jesus is not God, and the HS is not a person, and that the Scriptures are the ultimate rule of faith.
The reason they are accepted is because Jesus and the Apostles used them. There are many people, some of them officials, that do not follow the example of Christ.
No, it is the Apostolic Teaching.
Yes, but He was using the Septuagint. This is why He told those that rejected part of it “you know neither the Scriptures nor the power of God”. Many of the Jews of HIs day did not recognize which books were inspired.
Possibly. The Church surely is, since it is also “God Breathed”.
Try to avoid derailing another thread, ja4.
The fact that you can see there is more to the Apostolic faith than what you see in scripture should be enough to prove that Scripture was never meant to be complete. It seems to you that the faith of the Apostles is not the same as the Catholic faith for a variety of reasons. Sola Scriptura is the main cause of this misperception. Since you believe that all they taught is found in the NT, you are missing a lot of it. Furthermore, your posts make it clear that you do not understand what the Apostles, and therefore, what the Church teaches.
Because “derivation” happens in the mind of ignorant, fallible people. Even the most sincere person is limited by their own education and experience.