There are a couple of answers. One is that it's valuing what Jesus actually said over various conclusions people have drawn that may or may not be what he intended.
Another is that the Bible isn't inspired directly, but rather is human testimony to God's acts. In that case there's a difference between what Jesus himself said and Paul's advice to his churches. Paul was doing his best to interpret Jesus, and of course had talked to people that knew him, but I think there are also influences of his Jewish training.
It's simply not that case that all Christians, or even most Christians, consider the Bible as directly from God. Inerrancy is currently a conservative Protestant thing, not even held by all Evangelicals. From my point of view there enough issues in Genesis, OT history, and contradictory accounts in the Gospels to make it obvious that the Bible isn't free from human influence. I can't quite imagine why people continue trying to deny the obvious. That doesn't mean that it's all made up. The NT was written by Christians who had experienced Christ. I think the Gospels, particularly the first 3, give us a reasonably accurate picture of Jesus' teachings and actions.