Just thought I'd weigh in evanaurora. I'm a designer for a modpack that focuses quite a bit on representing indigenous cultures, especially native Canadians. We have quite a few leaders that people complained were "white washed", when in reality what happened was we took source images from darker skin colours, but it was the lighting of the scene that made them look lighter.
Take our takes on Henri Membertou of the Wabanaki or Cosijoeza of the Zapotecs - their skin tone is affected by the light and made them look lighter than normal. Same goes with Nonosbawsut of the Beothuk, Sheiyksh I of the Tlingit and anything else applicable.
In these Civ VI leaderscreens, there is a bright light coming from the left hand side of the screen and an additional camera light shone on the character themselves. I don't need to explain what happens to leaders skin tone's in that regard.
There's also always modding that can tweak Monty to become a bit darker.
The one thing I will agree with you on is the lack of Native civs in the base game. It may fit the whole Age of Exploration thing - but I find it pretty distasteful. Amongst our top priorities for modding Civ VI will mean the addition of a FN, NA, PNW or indigenous Australian ASAP to rectify this. It's probably the only thing really disappointing about Civ VI to me personally so far.
Also, I can pretty much tell you there was no whitewashing of our portraying of Benito Juarez. His skin colour was pretty light and was a native Zapotec to boot/