What do you think?
I think there is no criterion for importance. The people whom we consider important do not consider themselves important. Only others perceive them to be important. If importance is a matter of perception, you have to first perceive yourself important.
A person becomes an important figure in society by doing something that others think is "important". However, people do not set out to become important. Instead, people carry on their daily lives, interests, and work because it is a subject important to that person, and IF others see the work as important, the person becomes recognized. Often, people only get recognition after devoting their lives to a problem or a solution, or they get recognized after they are dead.