“Liberal” and “left” are terms of slightly different origin for the same position, opposing the established narrow feudal/monarchist elite power in favor of popular sovereignty and the government based on the rights of the individual.

It’s true that subsequently they’ve diverged with the old enemy being irrelevant, with “liberal” including and “left” excluding defense of concentration of power in the now-established capitalist elite justified by appeal the preeminence of the capitalist understanding of property rights.