Yes, there are definitely true things in the Bible. If there weren't, nobody would believe it now, let alone way back when it was being written. But what does that mean? Not really anything. Just because some of it is true doesn't allow you to infer that all of it is true.

Ever hear of historical fiction? Fictional events occuring during real events in history. While the story of Saving Private Ryan happened during a real war, and was full of real stuff, that doesn't mean everything in it was true. Heck, if it were that way, then Indiana Jones really existed, and the Ark of the Covenant is stashed away in some US government warehouse.

The existence of Jesus Christ is not completely assured, there are still people who doubt he existed, or feel it's a combination of more than one person who lived at the time.

Nobody has found Noah's Ark, and there is no geological evidence for The Great Flood (but many many regional floods). Besides, there are way too many logical probelms with the whole flood and ark story.