Your natural curiosity can lead you to expertise in many great and helpful areas, for yourself and your fellows.
If you will entertain some highly simplified expressions concerning the term polymath:
+ maths are subsets of language.
+ language is a tool of communication.
Thus, being a polymath, therefore, does not simply imply mastery, but also an ability to convey beautiful insights to others.
To crudely answer the topic question: to be a polymath is to inspire both yourself and others.
We are limited only by patterning and imagination.
Even if you are only browsing rough-cut coals, perhaps with the right inclinations you may find diamonds.
Knowledge and its accumulation are not the goal, they are tools to help you along the way. I am so thankful for all the many people who inspire and are inspired, for life is truly wild, and it is nothing short of a miracle that we have the ability to guide the growing and shifting tides of our existence.