No, I hear you.
You can't write dialogue for the screen the way you can write dialogue for a novel. Faramir can go on for paragraphs and pages explaining the history of Gondor and its significance to Frodo, but...you couldn't have a guy on screen do that. For one thing, it would be droning and static and boring. But for another, it doesn't accomplish the same thing. It sounds terribly unnatural to hear a lot of speechifying on a TV show. Even *famous* film speeches are typically quite short. The entire film 'The King's Speech' is about a man preparing and delivering a speech, and yet...how long does he actually speak for? (I don't know; I'd have to look it up, but I doubt it's a long speech.
Edit: 4 1/2 min. And in that film, it's basically the climactic battle scene. The real-life speech was
5 3/4 min. long, and the film shortened it while making it feel excruciatingly slow!)
So, regular dialogue is meant to be kept terse and to the point. You don't want to meander into a three sentence delivery with a lot of complicated sentence structure (usually). And you don't want to fill the page up with fluff over the 'how are you today? fine, thanks' variety for ultra-realism. People can't just be talking; it has to serve a point.
I don't find it too difficult to write (somewhat) natural-sounding dialogue for a story, but I expect to be able to include plenty of descriptive padding to get to what I need. A page of naval-gazing to lead up to the scene with the actual dialogue? Sure, why not, I can write that. You can't do that in a script, though - the internal thoughts of the characters are not easily conveyed. You can do the voice-over memory thing, where they hear someone's voice repeat something from earlier as they gaze pensively into the fire. But in general, you have to tell the story with dialogue, body language, and camera work [and you only get to put the first one into the script].
But as for creating scenes that people will care about, rather than just hitting the beats....that is what re-writing is for. You have ideas, you put them down on paper, and some of them fall flat. You figure out what is wrong with it, and then re-write. In
my first fanfiction with a plot, I wrote a backstory for Snape from the time he graduated from Hogwarts to the time of the fall of the Dark Lord (pre 7th book, obviously). The early part of the story involved Lucius Malfoy recruiting him for the Death Eaters. One scene worked really well - they were playing chess, and it was told from Snape's point of view. One was...terrible, and it was from Malfoy's point of view. I let my sister read it, and she confirmed my opinion - chess scene is great, other scene is a muddled mess. Once I figured out that Malfoy should be looking down on Snape patronizingly and adjusted his inner monologue accordingly, the scene worked much better. Still not as good as the chess scene, but it at least worked in my story. I hadn't gotten Lucius Malfoy's voice right because I hadn't really considered what his character was like in the story.
So, yeah, if you ask yourself what makes this difficult for the characters, what do they want out of this conversation, what assumptions do they have, what does the audience need to know about their background to understand the significance of what is happening, etc....you can usually identify the gaps, or the reason why a scene just does not work. And if you can't find it, you ask the kind people here to tell you what's missing
😉.