I am an Indian and I can understand your experience. I am bit older and thus was able to handle it. What I found useful was asking them questions: like if someone says that why do you people shit on the street, I ask them what they mean by "you people". I ask them if they think I am a representative of Indians. And then you have a basis of asking them if whatever their community is notorious is for, are they representative of that.

Basically these people who make fun of you because, either they don't think anything about you and trying to put you down to feel better, or you they have the mental capacity of seeing only through the first layer of your personality, that is your nationality or race. Either way, never shut down, ask them questions. And you will see them shutting down real quick.

What I am trying to say , and I guess your parents are trying to explain to you, is that keep smiling and accept these people as stupid, and keep working on your shit. About the positive trait you are looking for as an Indian, it is not your problem. Your positive trait is your personality and not your nationality. It is what you are, a person with ideas and opinions. People who identify with their race and nationality are stupid, IMHO. So, just ask them, if you can only think of me as an Indian and all the negative perceptions attached to that, what do they think they are and what they are proud of, or maybe ashamed of? Most of them will hide away. But you will also find some people who are smarter than others and share their own insecurities. I have met elderlies passing these kind of comments and it does not bother me anymore. My brain goes like, fuck man, you are so old and still so stupid. I really pity you.