I really, really want to answer your question properly, but I don't know what sort of answer you're looking for. Ultimately, my answer is because this idea explains observations and predicts new ones the best. That's MY reason for believing something true, but I recognize that other people use methods different than I do.

Give me a few examples of what you consider "mundane" and I will produce a few which I find support my ideas. A big one which I think would fit your needs would this theory explains why the highest quality and most inexplicably advanced construction is also the oldest. Many of the pyramids have poor quality on the upper and exterior areas, but larger and more precise blocks underneath.

I know I'm wrong about a lot of this, but I'm pretty sure my general outline is pretty solid.