I totally agree, however... if you're basing your holy book on stories that were passed around for the better part of a century by word of mouth before anyone wrote them down, they can't be considered historically accurate, or reliable.
It would automatically make the most plausible explanation for every miracle claim and prophecy the idea that it was all made up and exaggerated.
For example, if there was a real Jesus (Meaning a 1st century preacher). It's quite possible his followers were without food for a couple days, and he went fishing, had a good day on the lake, picked up some bread and was able to feed them all. Give that a couple decades of dramatization through word of mouth, and all of a sudden he's miraculously feeding the entire town with a loaf of bread and some fish.
By the time the Gospels were written, 50-100 years later Jesus could have been some kind of 1st century equivalent to Paul Bunyan or Big Joe Mufferaw. However, taken in a religious context, he would have gone from an influential preacher to a miracle worker, and even later than that, the Messiah. (Note: Jesus was not considered to be the son of God until the council of Nicaea voted on the issue in 325AD... and even at that it was a close vote. Prior to that, Jesus was considered to be a "mere mortal" like us.)
There are some good messages in the Bible, but there are plenty of bad ones too. I agree we should keep the good messages, however the superstition and bad messages should be thrown in the trash. Anyone with a hint of knowledge regarding how the bible was compiled and the how the early church worked knows that there is no way you can take the teachings seriously from a divine perspective.
Lastly, you are also correct that they serve as the pest evidence for a historical Jesus, as there really isn't anything else.... Unfortunately, these documents aren't reliable either.