You are allowed to be offended. That's a perfectly valid feeling and anyone that tells you otherwise is probably wrong.
But society places all sorts of restrictions on individual freedom. The trade been individual freedom and the power of collective action is the basis of society -- we agree to protect you from murder, and you agree not to murder anyone. We've long since agreed not to socially acceptable to call people names they don't like, unless that label is itself contrary to societal values and factual (i.e. murder). It's literally one of the first things we teach children, and it's a more or less globally held value.
If you'd like to change that belief, or convince us that your beliefs are tolerable in society, feel free to try. No one will stop you -- you've already posted to the public Internet and I'm reasonable certain that no one broke down your door and arrested you for that post. But if you hope to convince us though, you might consider avoiding straw men. No one is preventing use of the term "redskin", demanding reparations for previous use thereof, or even suggesting that such things should happen in the future. No one is suggesting that hurt feelings are a reasonable basis for legal decisions.