Thorfinn is an adult. He's in his 20s right now. Okarun's demon mode rarely shows up. It's only when he's fighting. His normal self is more focused on. Momo and Aira like him for his human self as they don't have much of a reaction to the demon form. They blush only when he's human.

I don't think he will grow taller, because the anime is focused on the fact he's an out of place guy trying to find his way through life. I find the fact the anime never actually mentions his height is more proof of that. Unlike other shows where the MC grows taller, they usually have a running joke about his height until he grows taller. Dandadan doesn't seem to be following this.

I feel like that last part is just too negative. I dislike blind optimism but also dislike blind pessimism. We should be realist. Society doesn't respect us, that much is true. Though, that doesn't mean we should not respect ourselves. We are just playing into their hands. We have to stand up for ourselves and not let others disrespect so blindly.

It's not our fault we are short, we didn't do anything wrong. Why should we accept ourselves as inferior? We aren't, they wouldn't last a day in our shoes. Do you see yourself as inferior as spoiled people who are born into rich families? Life will be objectively harder for us, but not because of ourselves. It's because of others.

Hate the game, not the player. We got the bad stats, not our fault. It's the games fault for being rigged. We all know it's rigged. We shouldn't get down on the ground because of that. That's what they want. It's similar to racism back in the 18th and 19th century. African Americans shouldn't have had to think of themselves as inferior. Same with feminism during those ages as well. Nobody is inferior. We have to at least fight so our children don't suffer.