From shoulders to hands, the human figure normally will have hands that sit next to the upper thigh area. However, some people have a lengthier ape index, which means that their hands can extend a little further down the legs. The best way to explore the different arm lengths is to work out a normal human figure with a light sketch using the rule of the head for scale. From there you can play around with shortening and lengthening arms to explore different body proportions. However, it is always useful to create a normal people drawing working with basic human body proportions, which you can then change and adjust from there. However, a good way to gauge how hands fit in normal human proportions drawing is by letting them fall next to the upper thigh.