The authors of the texts that later became books of the Bible certainly did not think they were writing parts of Scripture. Yet they certainly did think they were writing texts with authority for a particular group of people at a particular time. Others realized later that the texts had a wider audience and a higher authority. In that sense, the various writings became the Scriptures over time.
One of the continuing questions then is to what extent the words written for a particular audience are authoritative for other audiences. This is commonly expressed in the question as to whether every word and sentence is “inspired” but that leads to side matters about theories of inspiration. It is better to focus on the authority of the texts.
The truth of the Scriptures follows from its authority but its authority also presupposes its truth. Those who first recognized their authority had to recognize their truth, too. The two cannot be separated.
The question then is how far down does the authority and truth of the Scriptures go? That is, are each paragraph, each sentence, each word authoritative? Are the grammatical mistakes authoritative? The apparent inconsistencies? The language if not the concepts of archaic knowledge?
It’s best to start with the literary styles and conventions of the time and place of writing. These are not those of today, and are not the way “we” would write. But we should read them in context. Variations in names and spellings were common. Different authors writing of the same events may have a different purpose and take on them, and may adopt a different chronology.
All these are not “mistakes” or “errors” – they are differences, between them or between us and them or between them and other sources. So a correct understanding requires some historical background.
This goes all the way down to the words and grammar. The languages and usages are different from ours. The idioms and forms of expression are different. Some words are obscure. Some grammar is nonstandard. The writer may be writing in a foreign language they don’t understand all that well.
These are all cautions, not criticisms. They do not undermine the authority of the Bible but qualify its interpretation. There is no reason that the authority does not go all the way down.
Some will consider this excessive. After all, what does it matter if a few geographical details are mistaken? Or if some names aren’t right? It’s not for me to say how much it matters because what really matters is whether the Bible is authoritative. If it is, then it’s not for us to limit how far down that authority goes. The text is what we have, and the text is authoritative.