Less X than Y, where X and Y are nouns, is a structure that we use to mean "not very much like X, and more like Y" or "not really an X, but a Y".
So the sentence is saying, basically, "Looking less like Jupiter and more like Icarus, Emmanuel Macron came crashing down this week."
Yes, this refers to the characters from Greek mythology. Jupiter was the king of the gods; Icarus was a man who tried to fly too close to the sun and fell to earth. So the meaning of the sentence is "Looking less like the king of the gods, and more like the famous man who flew too high and fell to earth, Emmanuel Macron came crashing down this week."
Other examples: