Indeed, "我们有很多语言都是歧视兴的", but we could decide not to use that type of language. It is up to people, to use it or not to use it. I, for one, do not use “鬼子,乡里人,有病,笨蛋" and I believe you, and everyone else, can do that, too.
Your wish (I wish we can have a society without any discrimination too.) is one that can be fulfilled, with effort made by more and more people. For instance, because of the effort made, there was a Brown v. Board of Education event in 1954 which ended the racial segregation in this society.
阿Q的精神胜利法 is not a good idea. 歧视 is wrong, even if you did it once yourself. Whenever 歧视 is identified, it must be stopped. The problem is sometimes it's hard to tell whether something can be considered as 歧视 for it could be very subtle.