In what universe is having a big grin associated with being a humorist? The people in the top half of photos look more bored than serious, but Lincoln and Twain

In what universe is having a big grin associated with being a humorist? The people in the top half of photos look more bored than serious, but Lincoln and Twain with their set jaws, intense stare, slightly tilted/twisted head and expressive, engaged faces look like they're about to say something either deadly serious or seriously funny. Those bottom half ones would all be great modern photos, I wish I could capture people like that. Most of the subjects I photograph wind up looking either confused or goofy.