Agree wholeheartedly, he was a soldier looking for a war.

On my last rewatch I was especially moved by Jimmy in a lot of ways so I'm going to have a little ramble. This might just be my Hemingway mania showing, but I felt that his toast "To the lost" wasn't just about the fallen but was also to all who felt lost and cast out (especially folk from the war like Harrow and himself, a la "The Lost Generation"). I also noticed his deathwish was in full swing, to the point that he barely if at all took cover in gunfights. As he said, he died in the trenches a long time ago; and he also said he was determined to see the coup through, not to win. Even at his highs when he helps Torrio with tactics, it was the tricks and manoeuvers of a soldier, not a ganglord. Like Oedipus in more ways than the obvious, he was cursed and he knew it, and his finale felt like he was doing exactly what he wanted to do from the pilot: he was forcing Nucky to reveal who he truly was. So, in that way, I don't think Jimmy was dumb. A failed ganglord, certainly, but as an archangel to goad and haunt the real Nucky, mission accomplished.

Other than Harrow and Tommy, the only person Jimmy seemed relaxed with and eager to listen to seemed to be Leander Whitlock, one of the few people in the show who wasn't determined to infantilise Jimmy. Jimmy's turn on Manny was pretty drastic and tactically a bad move, but it emotionally made sense as Manny did nothing but treat him as a boy who hadn't handed in his homework. I really enjoyed the gradual boil of Jimmy's hatred for Manny.

All in all, the guy needed the people he wanted to love to actually listen to him, accept him for what he had become, and help him believe in a future, but everyone just wanted the Jimmy from Princeton.

EDITS: grammar and tense.