Is it normal to think that i'm alone?

I live life with the belief that I am alone and that all I have is myself. This might sound derivative or cliché but it has been easy living with this mentality. I'm not sure when I developed this mindset but I've had it since elementary school. I don't feel responsible for anyone nor do I feel dependent on anyone. The only person I care about is me (with my mother, and siblings the only exception). I hope this is isn't misinterpreted as being anti-social but at the same time I can't say that I'm any good at it either. Whenever I meet someone, I just put on facade and a fake smile to play along. I just feel that by only concerning myself with myself is pragmatic, organized, sufficient, and logical. It may be selfish, but it's not as if I tell people to "fuck off" or not help them whenever they ask. In a weird way(?) living with this mentality enables me to live with a sense of security and safety.