I'd go along with much of this. I looked at the image last night and the features that struck me:
The Towers: I wondered if this was set in the times of the crusades? Seemed to imply the Muslim world.
The Fool/Devil: I was struck that he had the hoofed legs of the devil. It looks a bit like a face on his belly with the tongue as a penis. I'm struck that he carries a sword, not something I'd have associated with a devil of a fool. I noticed the dice, and thought it would probably represent gambling. I'm not sure what he has in his other hand, it looks like it might be a ribbon from the knight/horse, so perhaps he is stopping the knight, although it doesn't really seem to make sense as to how it would be attached or what it might be.
Knight/horse: I too was struck by the snake like feathers and tassels, and had to zoom in to be sure that it wasn't absolutely the intention of the artist to have it be actual snakes. The knight looks like he has "just entered" the scene. I'm not sure if he is coming into a new land/city through the castle wall, or whether he has just left the safety of it (which seems more in keeping). It looks like a bell at the back of the horse, I'm not sure if it is attached to tassels or to the horse, but it strikes me as odd to see in that place, and on the knight at all. I would assume the association with foolishness. I like the mustache on the knight, it reminds me of Vlad the Impaler.
Murder Scene: Not much to say, it looks liks someone is about to be clubbed to death. The victim seems to have a nice robe and hat, perhaps a gentleman? I'm not sure why the murderer is committing the crime. They don't look like soldiers fighting.
Additional figure with battle ax: I have no idea.
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I would guess that this is some warning about strange and exotic lands, quite possible the muslim world, quite possibly the crusades. Apparently, one will likely meet devils out to trick and fool, murderers, and enemy soldiers.
I am still bothered by the snake like look to the knight, and wonder if it mean Pride or something because it makes me wonder if this guy isn't necessarily a hero?