LOL
https://en.wikipedia.org/wiki/369th_Infantry_Regiment_(United_States)
I read that before posting, coz it was mentioned earlier, lol. If you think 1 regiment of country which joined war in its last year should make it perfectly fine to picture mainly european conflict like black people were actually a thing in it, you can very well picture medieval Spain as half black, because, there was thousand or so moors living out there at the time.
There was balcks in first world war, sure, but the were (extreme) exceptions, not something common. And again, where is french who was main european fighting force since days of Charlemagne and played main role in said conflict? Nope, no french, better introduce some irrelevant black guys for correctness quota.
The only way i see that cover guy justified if they make campaign about him and his regiment, which would actually be quite interesting if represented in certain light, althrought I would easily prefer ottomans over them for their fancy hats and uniqueness, because, again, ottomans was a real thing in that conflict and Gallipoli campaign was hell of a fight.