I am trying to make a scene where I need a crowd of people. It's very hard and time consuming to create each character. Is there any simple way for doing it.
Copy the script from here: How to set a random value for multiple shape keys? and paste it to the editor window. As you can see, all the shapekeys values changed randomly, creating the unique mesh.
In the Shape Keys panel click on the arrow icon and choose Create duplicate for editing option. Now you have new unique mesh, with all the shapekeys applied. You can generate many of them very fast. The more shapekeys you have, the more combinations there are. Good luck :).