Well, that much I agree with (your last paragraph). I think that Hindenburg and Ludendorff were strongly agitating for war for quite a while and I'll go so far as to say that I don't think you can call the Schlieffen Plan, which went into great detail about exactly how the German armed forces would sweep through France like a swinging door, right on down to the levels of supply each army would receive each day, a plan for a "defensive war". I do think that Austria-Hungary did proclaim war a bit too loudly but I also think they were egged on by H-L into doing do. I think that H-L also thought/gambled that England would stay out of the war entirely or else would pull out of it once the German might became too oppressive for them or something, and all in all I am 100% positive that nobody on either side had any notion that the war was going to be the meat grinder that it became.
Another point to be raised there is that in the US at least, Germany is so obviously the villain in WW2 that it's easy to put them in the same role in WW1, particularly since we ended up fighting them (in part because of a largely trumped up telegram that was sent to Mexico to try and get them into the war on the side of the Central Powers). The reality is that the Great War did not have cut and dried good guys and bad guys the way that the Second World War did; atrocities were committed by both sides, the worst of which being, ironically, perpetrated by those same Serbians whose own oppressed status helped lead to the terrorist attack that started the war. I feel like when you have a situation like this, it's a decent narrative exercise to present things, at least temporarily, from the other side's perspective, and I give Carlin the benefit of the doubt here in saying that that's why he opened up with a POV more sympathetic to the Central Powers than you might have preferred.