I'm not sure as I haven't read it specifically. It might be about a man who is distinctively recognized by not wearing a hat, and perhaps his adventures, relationships or some kind of personal journey could be central to the story.
I don't know who the author of 'the man with no hat novel' is. There are so many novels out there and without more information, it's difficult to determine the author.
The characteristics could include a hat that stands out, perhaps with some unique design. The older man's face might have lines that suggest experience and wisdom. His posture or clothing could also contribute to the overall look.
A man with a monocle and top hat in cartoons is usually portrayed as someone who is formal and maybe a bit stodgy. The combination of these accessories suggests a traditional and possibly stuffy personality.
The blue hat man cartoon could have multiple interpretations. It could be a character designed to evoke certain emotions or convey a message. Maybe the color of the hat indicates his mood or status. Or perhaps it's all just for visual appeal and doesn't have a deep meaning.