It is common for young children with autism to have social isolation issues. This happens because they miss the link to communicate. Yes, some children give hugs, smile, laugh at appropriate times which is something, but you need to give your child an opportunity to structurally learn these skills early to build for their future. Early intervention is extremely important to help decrease this and increase awareness. It is not easy for a child to learn this, but they can learn it.
But your child needs to learn the basics before jumping ahead or it will be harder for he or she to understand the concept. When your child is ready you can introduce visual stories, role play, use video modeling, and even use adaptive material as props to make it more real. If your child is capable and ready to have interaction of somehow with another child, a good way to do this is with a trained therapist to guide the play.
Once your child has some understanding of the world around them and more aware, communication can become more frustrating if they are not taught how to do it. It does not have to be using expressive language, it could be using signs, pictures, or even augmentative communication devices.
Motivation is a very important part in teaching children with autism. It can be having your child pick a play activity where you can incorporate taking turns, and or using highly preferred reinforcement to learn. Music therapy is also becoming popular. Over the years I have found that children with autism tune into music and love it. You can dance, follow instructions, play games which all can incorporate interaction between one another.