The main aspect is tension. Read up on the Three Act Structure, or Save The Cat, which similarly shows the structure of screenplays.
You have to introduce characters and their "normal world". Even there, you need a little tension, little problems for them to solve, so the audience (reader or viewer) is anticipating something. But these are not the main story, watch movies and you will see that the first things characters are doing are NOT usually about the main story, they are about something different. A previous case, or getting the kids to school, whatever.
Usually, in the normal world, you give your MC (Main Character, sometimes Main Crew) some kind of important strength, and some kind of important weakness -- By important, I mean the weakness is going to matter significantly in the story, it isn't a weakness like "I dislike the color orange."
Then you introduce the main problem; this is often called the inciting incident. The first hint that something bad happens. Sometimes this is in-your-face (Alien spaceships arrive on Earth), sometimes it is more subtle (a man's wife decides to call in sick, she thinks she has the flu).
The MC tries to fix the problem like any other daily problem. The flu gets worse, we go to the doctor.
The inciting incident escalates to the point that the MC can no longer continue their normal life, it is too big, and they have to leave their normal world and routine, sometimes metaphorically, sometimes physically as well. They are operating in new uncharted territory. If you have picked their strength and weakness well, their strength only helps them a little, and their weakness impedes them a lot.
Tension is sustained by the MC having goals (to solve the main problem) but failing to achieve them. They can be very good, they don't have to be incompetent, but the problem just does not prove EASY to solve. Often they have to learn something, or track down some knowledge, or solve a puzzle.
Tension can be increased by new problems, roadblocks and complications.
But eventually, the problems start getting solved, new information comes to light, and there is a finale, usually with the MC risking everything, in order to achieve their goal.
The main aspect of a story is some kind of tension, it is people dealing with something in the world that is not right. Usually in a story, we have several ranges of tension; we want short, medium, and long range tension.
Short range tension is about the next few pages, the scene we are in. We turn pages to see how it turns out. This can be as simple as wanting to see how an argument turns out, or a romantic conversation, or how a character deals with no hot water when she wakes up and wants to take a shower, in winter.
Medium range tension is about the chapter or Act (about 25% of the story). We want to get to the next intermediate climax, a major achievement or setback that changes the nature of the story.
Long range tension is about the book, of course, how does the MC finally overcome the problem, first introduced by the inciting incident (which occurs about 10% to 15% of the way into the story, by length).
Whether you devise all these up front, or just know where they need to be, stories get boring when they have no tension, meaning the audience isn't wondering what will happen next, has grown bored with too much description, too little risk taking, too much backstory or history or pointless pondering.
In the beginning, they will give you more leeway, they understand they need to be introduced to characters and the world they live in. But that benevolence fades quickly, they want action, problems, angst, goals, worries, resistance.
I suspect what you are missing is one or more of these tensions (short, medium, long range); inventing situations so they are always uncertain as to how something will turn out. Even if that something, for short range tension, is not truly important to the story at all.
Typically stories start with short range tension, I call them "throwaway problems", that serve to help introduce the MC and their world, and can carry you to a medium range tension and the inciting incident.