If it's not all true, like the literalist Christians say, then I don't think any of is necessarily true. But there will always be the prophecies. Even with them there are the Jew, Christians and Baha'is that interpret them different.
So my opinion of the 10 Commandments... not necessarily revelation. They are mixed in with historical stories and then the six hundred plus laws sound more like people made them up not God. The Psalms? Religious poetry. The Prophets? Who wrote the stories? Most sound like they were written by someone else, not the prophet. Some, like Daniel have historical things added in that include him being thrown to the lions but not harmed, his friends thrown into a furnace but not burned. Then Jonah, he refuse to deliver a message to the people of Nineveh and gets swallow by a big fish. The Historical stories are mixed with God's miracles. Like where God stop the Sun in the sky for Joshua.
All of it is inspiring and full of "truth" for Bible-believers including the Historical stories. So where do we draw the line on what is truly from God and what came from people. And that carries over to the NT also. That's why I ask Baha'is about the miracles of Jesus. Baha'is have said that the healing of the blind met those that were "spiritually" blind. I don't believe that is what the writers meant at all. I think they meant it as being a physically blind person had their sight restored by Jesus. For a Christian, they take this as being literally true and "proof" that Jesus was who he said he was, The Messiah and for a lot of them part of the Trinity.
For them is has to be all true. For Baha'is, you really don't need it at all. Like you say, you've got new teachings that makes anything taught in the Bible, even if totally true, irrelevant. I don't need any of it to be true at all, and if not true, my best guess as to what the Bible is... is that it is embellished, mythical stories. Which could very well include their God being mythical too.
This thread seems to be finally slowing down, so I'll see you on some other one.