The Arduino can read any kind of sensor. It is simply a matter of choosing the correct sensor. Distance can be determined using an ultrasonic sensor, for instance. What is at that distance is a much bigger challenge.
For the Arduino to track a person, the person must be wearing something that some sensor can track, like an IR beacon.
It's unlikely that you want the users of your system to wear anything that makes it possible to track their motions.
So, it seems unlikely that the Arduino will end up being able to do much.