What happened was science started disproving large chunks of biblical myth?
Nope. The Church has always been fairly flexible on that point. Catholics and Lutherans aren't literalists, like Fundies are. And, there is little "Biblical myth" that can't work around scientific knowledge.
So proving people can't walk on water, come back from the dead or bring people back to life. Or how about pretty much every single other word printed? At which point do they hold their hands up and say "Ok, yeah, it's pretty much all bullshit" cos I'm patiently waiting.
Could be some dude here or there wanted to jump on the Jesus bandwagon and get his say by making the story a little bit more interesting. I'm not exactly sure what you're looking for here. The faithful who are receptive to science will reinterpret scripture to fit the science. It might be a hell of a logical pretzel but they will do it, and it will be consistent and will define the impossible as metaphor. Christians are pretty smart in general. In general, of course. They actually do want to understand how the whole thing works.