I could agree with the mixed bag message in cartoons. But not movies and tv. From the 70's on, it seemed that they were anything but villains. But the point is that is the exact opposite of how orcs were in the primary texts.
We seem to be playing a weird game of whispers here.
The point made earlier was that Orcs sometimes filled a structural role that Native Americans had once filled. One of the reasons you would use Orcs to fill that role is because you are no longer comfortable filling that role with Native Americans.
If you want a story about savage attackers mounting a bloodthirsty raid upon homesteaders on a frontier, then once many writers would have had no qualms about making it a straight historical (or not even historical if you go back far enough). If you feel that you can no longer have that story without addressing it with more complexity, then moving those homesteaders to a fantasy world and having those savage raiders be Orcs rather than Native Americans is way one to avoid that. You can still tell the same basic story of terror and heroism under siege that you could once tell, and you don't have to worry about thorny questions that might be arising in the historical version of why the Native Americans are raiding, or whether the white settlers ought to be there in the first place.
The point here is that Orcs are NOT Native Americans. It doesn't work if they are. In many ways the less they resemble real Native Americans in terms of things like cultural details the better for the above purpose.
Of course what happens is that the structural simularities get noticed and people may start adding native American elements to their Orcs to flesh them out. And once they do that, they may also start adding in some of the historical complexities as well, so now Orcs aren't all evil, and maybe the settlers are moving in on their land as well (or they remain evil and the portrayal gets increasingly racist, or they get turned into noble savages etc).
Also because they are NOT Native Americans the Orc vessel is very malleable. It can be different things in different times. There's lots of alternative ways the details can be coloured in. Lots of places and situations can have savage raiders, so there's plenty of alternative caricatures that can be added to Orcs.
Consider how R.E.Howard uses Picts in his Conan stories. Here we have a writer who is really making no effort at all not to be racist and is steeped in racial ideas. His picts are based off conceptions of barbarians beyond Hadrian's wall, but the pictish frontier is clearly in many ways a western one, yet in other stories (such as his Pirate Story, the Black Stranger, the parallel seems more African). His picts basically fill a structural role in a whole lot of different colonialist myths.