It is a collection of related literary works. It is a stream of progressive revelation of God's dealings in history. There are textual issues to work through, as in ALL historical writings. The speaker indicated that is was a real problem. The clarity only gets 'better' as we learn more and 'dig up' more.
Linguistic conventions apply.
The gospel writers probably had to synthesize and select down, from a large corpus of material. It has a cultural setting and background, that forms both context and 'target'. Literary units have genres and styles that sometimes give us 'clues' as to how to understand them. The writings are Related in many ways. All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness, Rom.