You're doing better with the format. You recognize that it still needs work. And you're right that the dialogue continues to need work. But ignoring that, the chief problem is that you don't tell a story. The medium is not the issue. The problem is you aren't a storyteller. You throw lots of description at your readers but they are meaningless because they don't convey a story.
I had to force myself to read past page five. It was, frankly, boring. Talking heads involved in idle chit-chat that doesn't move forward any part of the story. That sequence seems to be pasted in an unmeaningful way to the preceding scene with the medicine man. While the healing scene was interesting and started to draw me in, the subsequent section left me scratching my head and quickly lost my interest with the very bland conversation.
While it can be hard, practice writing with an act structure. Just as all the great artists first learn to follow a "standard model". Once they've mastered that, they can go off and be very creative. You can do that with other stories. When you have perfected these trial scripts, come back and tackle "Jaw". The greatest challenge I find with students is they believe they need to be perfect right out of the gate. You're allowed to make mistakes. That's how we all learn.
You show great creativity. And you are very visual. I think when you do make the step into filming and directing "Jaw", it will be visually impressive. But to really knock off the viewer's socks, you need to be able to tell a good story. While I believe you have that in your mind, it doesn't come across in the script. You want to somehow link these segments. You might use the boy, a crow, etc. Then when the truck passes the boy or raven it's linked, however abstractly, in the viewer/reader's mind. You need to make the dialogue immediately relevant. By page 10, the reader/viewer needs to be gripped, have a sense of the movie, and have met the main characters.
As you present it at the moment, I was confused, lost interest with the small talk that made me feel like an outsider, I got no sense of the story as cohesive, and I was unsure who was the main character(s) and who were simply supporting characters. Also, the visuals of the medicine man were disjoint. It's like you kept changing your mind if this was the boy invoking a spirit, if it was a 'monster/demon' and then you present the image as a medicine man. That may have been intentional. However, it seemed very disjoint in the script if that's what was in your mind.
You have talent and the script has potential. I've seen improvement since your first post. You just need to take time to develop the basic skills. You can't be a master craftsman without building a few smaller projects first. Every type of writing has a structure, and screenwriting is no different. The act structure is rigid at first, but it is just a training tool which becomes a useful framework for any master screenwriter even if not followed exactly. It helps to fashion a concise story flow.
Keep writing. Cheers.