Yes, in worst case (no learning for German until Balkan war) their advantage over Russians will be less than dramatic. But it is an exactly worst-case-scenario for German.
As about khaki and general protection of infantry, i think this is a story of too much butterfly effect. Cannot predict anything if deviating outside OTL. Small ideas making big differences. For example, the France being the last one to accept camouflage was the first to accept a modern helmets (more important in trench warfare than camouflage).
https://en.wikipedia.org/wiki/Adrian_helmet
As about battleships being junk, i mean what WWI was decided in land combat far from shores, and any battleships (modern or not) contributed nearly nothing, their efficiency sapped by mines, coastal artillery, torpedo boats, destroyers and spotting airplanes. Even merchant fleet hunting was done not by these monsters, but by U-boats, destroyers and light cruisers. Direct analogy to modern ICBM. Powerful, expensive, frightening, vulnerable and unusable.

By the way, by mentioning need in destroyer escorts you indirectly agree what battleships in WWI has become a specialized assets.
P.S. Colourful uniforms were designed to give advantage in melee. Identify Friend Or Foe by peripheral vision reliably, and keep your line more accurately (and therefore deadly for enemy). Also, simplify control for commanders as they know where their troops are (so can move them with less confusion and less delays, outmanoeuvring khaki opponents). Finally, bright uniforms lessens friendly artillery fire incidents (which were widespread in WWI as communication tech lagged after the increased range of artillery). Fuinally, in trench warfare the colour of uniform is less than relevant, as everything becomes the colour of dirt. Taking into account all the factors, the adoption of khaki give not so clear advantages as dummy fire tests may suggest. May be 1.5-2 times reduction of casualties during entire war, depending on war manual fine details. If somebody has advantage in artillery and mobility, but not in radios - then the khaki are less than advantageous.
P.P.S. Basis equation for combat efficiency of field weapon: kill/cost ratio of weakly protected targets is reverse proportional to calibre of weapon. What`s why everybody used rifles, not grenade launches as main weapon. For same reason, main field artillery was 3-inch, not 8-inch monsters. In this respect, battleships are cost-ineffective against ground troops even if allowed to go to shore bombardment unmolested (which did not happened in WWI). Remember the Gallipoli Campaign. The British battleships bombarded the Ottomans incessantly and without naval opposition, but it was not enough to win. For same reason the cluster weapons nowadays are so efficient - they reduce the effective calibre of bomb to calibre of each bomblet, resulting in smaller overkill zones and superior kill/price ratio.