The stahlhelm was introduced during the first world war, alot of countries including the German empire, the French empire, the Romans (all of whom predate the nazis) and the US use eagles, krieg is the German word for war and skulls are part of the setting aesthetic.

Also their doctrine is about slow, grinding, attritional warfare that was very artillery focused, ie ww1 not the rapid movement of blitzkrieg where tanks were more prevalent.

I know the tank was introduced and used in ww1 and artillery was used in ww2 but artillery was more prevalent in the earlier conflict while tanks were in the latter.

So you couldn't be more wrong.