The foundation of Christianity is not Bible stories. The foundation of Christianity is the belief that a man named Jesus walked the earth. Jesus was God in human form. They believe he showed the world that he was God by predicting his own death and resurrection. This one story is the foundation of Christianity.
Different denominations of Christianity differ in how they interpret old testament stories as literal or allegorical. What you are referring to in your question about believing all the stories is a question of biblical literalism. Evangelical Christians, which are about 1/3 of all Christians in the US often believe in the literal interpretation of the Bible, i.e. the earth was created in six days, Noah's Ark was real etc. Other denominations interpret these stories as allegory.
Yea. Those are claims.
1. Do we have any first hand acounts of Jesus resurrection? No.
2. What about Jesus miracles? Is there an outside source(s) that talks about those miracles? No.
3. Are there MAJOR contridictions in the bible? Yes.
4. Do we have the original sources of the bible? No.
5. Was the life of Jesus a game of telephone for well over 40 years? Yes.
6. Who wrote the 4 main gosspels? Matthew, Mark, Luke and John. Not a clue.
What I beleive about the historical Jesus is he was an apocalyptic prophet. Our earliest sources Mark 9:1 and 13:30 bear this out. Our earliest sources M, L and Q are laced with end time predictions. Who did Jesus hang out with when he first started his ministry? John the Baptist. Who was John? He was an apocalyptic prophet. Paul 1 Thessalonians 4, and 1 Corinthians 15 expresses that Jesus will return in his life time. The apolyptic message from Jesus in Matthew, Mark and parts of Luke starts to get changed from the coming kingdom, to the kingdom within ourself which is expressed fully in John. Parts of Luke as well. When we look at the key in the middle of this. The history from that time period we see the Jews being oppressed from just about every surrounding nation. The Assyrians, the Babylonians, other neighboring tribes and finally Rome. The message was just hold on a little bit longer because God is going to come back, smite the enemies and bring a new kingdom here on earth. That was the message at that time. And so, when I look at all of this its very easy to see Jesus as an apolyptic phophet.
Most Christains are unaware of this view which is believed from just about every respectable NT scholar today. A HUGE contributor was the book: "The Quest of the Historical Jesus." by Albert Schweitzer.