I ain't no expert, but I ain't no doorknob neither, and it seems increasingly clear to me that there are two critical Truths to this whole screenwriting thing:
1) it's not really that complicated until and unless some babbling morons shows up and works double damned hard to make it seem so
2) there is some odd element to the process which for lack of a better word I'll just call "Magic" and then leave others to argue about.
I do NOT mean magic in the rabbit-out-of-the-hat kind, nor of the actual conjuring impossible bits of metaphysical weirdness, but magic of the sort that is the spark of inspiration and creativity—that thing that tells one artist to paint the sunset in THIS manner and another artist of equal experience and technical ability will paint that same sunset THAT way.
We are all each of us the flickering momentary quantum result of every thought and experience which has led to this moment. We bring an infinitely weird and varied pile of memories and impressions and fears and dreams to every issue, and when you tell the psyche to sit still and create an Entire New World out of sheer thought and imagination, the results are going to show wild variations, and some of these variations are going to be critically important to making one particular vision of this potential world somehow more alive, more fascinating, more deserving of our thought and attention as audience members.
There are any number of paintings of Christ's last supper with The Disciples, including great many by undeniably talented artists and craftsmen, yet when we speak of "The Last Supper" it almost always refers to a specific singular imagination of this moment: the one which Da Vinci's peculiar and specific genius gave us.
We can sit around and argue and theorize the whys and wherefores of his specific genius, or we can just as effectively wrap them all into a bundle and label it "Magic" (or choose your own damned word) and wind up with much the same results when we try to sort out how and why inspiration works the way it does.
The trick—such as it is—is to develop the skill of putting yourself in whatever specific mindset it takes for you to enjoy maximum possibility of that divine spark finding your brain and then catching that spark in words, or pictures, or dance, or seafood cooking, or stainless steel welding, or whatever.
The Magic is not what's rare. What's rare is the awareness to recognize it and the willingness to improve our skills at receiving it and channeling it into some durable medium where anyone else—"the audience"—can share in our little glimpse of the magic that surrounds us.
If you can do that—if you can recognize where your Magic is strong and where it needs work and then set yourself down a dedicated path to improving what can be improved and finding ways to overcome and circumvent what weaknesses you are truly incapable of improving—then you have a fighting chance so long as you refuse to quit.
Meanwhile, shut up and write. Product is the point.