Ben is not even written to be a smart person, he's very misguided that some of the main cast calls him out on it. Does he change throughout the story? I don't think so but I'm kinda hoping there would be a trajectory with his character where he ends up becoming an anti-villain of sorts, it'd be different to see that.
While I agree that he's not the smartest, I do believe he's supposed one of the smart ones (in my opinion at least). Maybe not school smarts, but some of his insights and ways of thinking along with his daydreaming habits tells me he puts a lot of thought into what he does. He doesn't always necessarily act on them, or think about consequences too much, but he does at least think about them. To me that seems like he has the capability, but who knows lol maybe I'm not that smart either 😅