Liberalism has both economic (free market) roots and political roots. The first "leftists" were the French revolutionaries and they wanted (political) freedom as well. The reason liberalism is in the "center" is because both left and right tried to appropriate it. (Although I think liberalism, in the sense of individual freedom, is a distinct value from other values such as conservative/authoritarian or socialist/communal.)

Individual freedom absolutism is best refered to as "libertarianism" right now. Which, btw, is a label the right appropriated and the left gave up.

This terminology change is mostly limited to anglosphere. Outside of that 'liberal' is still commonly used for economic-right low-intervention position.