Silly putty was created by accident when we were looking for a replacement for rubber. During World War II, Japan had taken over many rubber producing countries and so the United States was looking for an alternative.
Silly putty has many other uses. It can be used as a glue. This ability makes it useful to pick up dirt, lint or even ink. At one time you could lift the ink off a newspaper for a perfect copy of some words or a comic strip image.
Many rehab clinics use a form of putty for rehabbing hands. Forming and reforming putty is a way to build strength in injury weakened hands.