They seem all be to be on the muscular side, unlike most contemporary depictions who show them more normally proportioned.
Nobles (or renowned warriors) wearing these full body dress are a good idea, and can be also used for Jaguar and Eagle societies, just with different heads. If in doubt due to the textures, leave the feathered body out, as it takes up one sixth of the sprue and will be repetetive if there is only one anyway. A slighty grainy structure will work for linen and fur, perhaps even for the eagle warriors as many of them probably used eagle feathers mainly on the head and not on the whole body. A conical headgear would be appropriate.
I would not waste sprue space on banners, standards and other personal significers as their trademark was that they were as distinct from each other as possible, and whatever could be on a sprue on typical equipment would be better then numerous identical “unique” standards. If you want to go there, add a simple carrier construction that fits on some backs that can be kitbased stuff on the top.
You should definitley try to cover Tlaxcalan and probably other Mesoamerican types (Huexotzinca, Chinantec …) , too, which will mainly mean some different heads for the warrior societies and weapons (here bows definitely come in).
As there are many unique characters in the Mesoamerican armies, especially commanders and priests, you should not try to cover all of these on a plastic sprue but just try to complement existing metal ranges. As you already do that with some other plastic sets I am sure you will avoid the trap to attempt too much…
For literature and equipment I suggest Ian Heaths " Armies of the Aztecs…" from Foundry Press, alas only available from the collectors market. For very illustrations (and content) there is also Miguel Gomez “The Mexico Conquest”, available from Andrea Press (only from there, atm, but at a 50% sale right now).