I guess you want to be offended don't you, cause you are looking for offense where none is intended. So how much does that job pay? Does someone pay you to look for offense or to be offended? Because I got a real job that pays real money, I don't look to be offended by every little thing, because I can't earn a living doing that, and it does not profit me to do so. So why do you look so hard to find offense? Don't you like to enjoy yourself every once in a while, that's all I am here for, how about you?
For your information I have not used stereotypes, in fact I have gone out of my way to avoid them. To suggest that American Indians would form armies, use muskets, build wooden ships and explore and conquer various parts of the World is not using a stereotype about them that I am aware of. Can you produce a single Indian that would be offended if I suggest that his people can do great things? if you can, then I would bet, he would be a very small minority among his people.
If you are not an Indian, then you have no right to speak for them or to be offended for them. If any are offended let them speak for themselves! The purpose of role playing is not to offend people. This is alternate history for one thing.