What you say is just the 1914 wartime propaganda that was re boosted during WWII in order to minimize the Versailles Catastrophe and put Germany as the contemporary bad guys.
You state that Germany's war declaration on Rusia was unnecesary. However you do not mention that Russia's declaration of war against Austria was more than unnecesary. The russian intention was not "save" poor Serbia but to gain access to the Adriatic and open a seaway for it's Black Sea Fleet throught the Bosforus. The russians supported and boosted the Serbian Inteligence's terrorist agenda into the Habsburg Empire.
You also fail to mention that it was the Serbians those that infiltrated a terrorist cell in Sarajevo with the express target of killing the Archduke and produce and international crisis. A crisis completely artificial that was required by Rusia and it's ally, France, in order to smash into the heart of Europe: Russia for the already mentioned motives whilst France needed allies in order to take revenge against Germany for the superb kick it gave against them in 1870'-71. France knew that never, ever, their supremely incompetent army could deal, alone, with Germany.
You also fail to mention that Germany was bound to Austria the same way France was with Russia. Let's assume for a second that France and Russia were decent in their intentions: still France had to go to war against Germany because of their pact with Russia. So Germany with Austria.
If one war declaration was unnecesary then both were the same.
And Edward Gray was, in at least one ocassion, called to attention by the Parliament because of it's anti Germanic stance. And it's even more than clear that the invasion of Belgium was a move that both sides considered as necesarry to wage their war. The Germans had to attack, as Israel had done late in the same century, because they had to prevent two offensives in two borders. Simply put, the Germans got there first.
You also fail to mention that Russia's action was 100% offensive and was only thwarted by their own incompetence and because the proficiency of a dark Prussian colonel at Tannenberg.
An appeaser is one who feeds a crocodile, hoping it will eat him last.
Sir Winston Churchill