Theists: What is your stance on evolution?

[Angrboda]

What other conclusion:  The brain started functioning without a blueprint for its development, and the mind and consciousness came after the physical organ?

Yes, that sounds correct.  If you look at the structure of the human brain you'll see that it's a collection of smaller organs with a fairly clear developmental history.  Low in the back you have the more primitive sections, the so-called "lizard brain" that acts as a switchboard of sorts, processing stimuli and triggering the release of hormones if a threat is perceived.  Higher mammals, including humans, have the prefrontal cortex.  This is the area of the brain that can override instinctual reactions and dictate a more rational one.

As I see it, the brain had to evolve to a certain level of complexity before it was capable of generating what we call "consciousness."

What if its a sliding scale such that the further back you go there are simpler and simpler versions of consciousness but it never is ever not present in some rudimentary form?

Ultimately it depends on what consciousness is. If a thermostat is conscious in some sense, then it's unlikely there was a tipping point.