The oral word preceded the written, and the apostles provided the authoritative interpretation of the Old Testament. Which, BTW, included the books of the Maccabees, Judith, Tobit, etc.
What was scripture and what wasn’t scripture wasn’t settled for 300 years. The Word of God is part written and part unwritten.
I think any reading of the early fathers of the Church will demonstrate that the common Evangelical reading of the Bible would have been foreign to the early Christians.
Yes, they interpreted some things, but the Old Testament Scriptures had been considered authoratative by God's people for centuries before the apostles were born.
What was scripture and what wasn’t scripture
Paul's writings, for example, were anointed scripture from Day One. The decision to incorporate them into a book wasn't decided for some time, but they were scripture well before that.