Is it normal that i'm always left out?

I don't think the poster that you were responding to was attempting to diagnose anyone - only asking if that might at least be a contributing factor to the problem of making friends or fitting in. I know it's difficult to believe, but some people actually are on the autism spectrum, and you wouldn't even necessarily know it. What used to be called "Asperger Syndrome" (I tend to think of the TV character, Sheldon Cooper, as the poster child for this disorder) is now just lumped in with all the other autism spectrum disorders, as if they were all just one thing. However, I still prefer to think of it as "Asperger Syndrome," and many individuals with this syndrome are very high-functioning, intelligent people, and you might not even realize they had anything particularly "wrong" with them (though you may observe that they tend to be different from neurotypical individuals in regard to their social interactions with others). As they mature, they can usually figure out how to fit in better than they did when they were younger, but they still have problems making and keeping friends, or fitting in with a group. The OP, or the many undiagnosed others on the spectrum, wouldn't necessarily know if they had "Asperger Syndrome," unless they were evaluated by a doctor. They only know that they don't fit in and for the life of them, they can't figure out why.

Yes, everyone feels left out from time to time, but for those on the spectrum, it is pretty much a constant struggle throughout their lives. Many eventually give up on having friends at all because it is too exhausting to keep up the pretense of being just like everyone else in an attempt to fit in (which is what most people seem to expect from those they call their friends).

I was asking a question. Settle the fuck down sailor.