My 2yo son does not seem to be too social. He cries when he meets new people and doesn't want to play with other kids his age. What is happening? Is this normal?

It's absolutely normal. He is just 2-year-old and you are expecting too much from him. Different kids have different understanding and acceptability of socialising. Some kids are very playful, like people around them while others like familiar faces and their own home set up. Don't push him into doing what he doesn't want. If you will do this, he will become more cranky and cling to you. Let him take his own time to open up. And if he isn't comfortable, let him be. He is just two, may be, he requires more time to develop interest in social mingling. I think take him out to the parks, malls, zoo and kids friendly places more often, not to mingle with kids or new people but just to get used to the environment that has new faces, kids, animals. Let him first be comfortable with the environments that are different from what he sees at home.