So yes, they very much expected that a liberalization of government economic regulation would help the common man. The thinkers from the Enlightenment--which is the philosophical movement you have to understand in order to "get"the evolution of liberalism in the 18th century--spoke of the "natural aristocracy" or people who were naturally talented and who's ideas and enterprises were being held back the interference of conservative governments. The governments at that time were mostly in the hands of the hereditary aristocracy, not the naturally talented.
Sounds like libertarianism? Sure, they share common roots. If Jefferson woke up and dug his way out of his grave today, he'd probably vote for Ron Paul. Where contemporary liberalism split off from classical liberalism was when those natural aristocrats, liberated from hereditary power in Jefferson's America, managed to take control of the government in the Industrial Revolution and Gilded Ages. Then liberalism, called Populism and Progressivism, expanded its ideas to include protecting the little guy from the abuse at the hands of corporate power.
Apparently, they found out, Robber Barons are just as bad to the common folks as regular barons are. Once they get money, they get power and they influence the muscle of the nation-state to secure and accumulate more wealth for themselves. The Progressive answer in the early 1900s was to rally people-power to regain control of government and use it as a restraint against the abuses of money-power, just as the Bill of Rights was written to restrain the potential abuses of government power. The common theme shared between the 1791 liberal and the 2012 liberal is to protect the individual from whoever oppresses him so that all can live up to their full potential.
The common theme between the 1776 conservative and his 2012 counterpart is that both want to secure the social order so that established powerful interests can maintain an orderly society. The conservative of 1776 wanted to see the wealthy hold onto the power of the state--whether colonial Boston or Bourbon France--by which the elites pulled down more cash. The conservative of . The conservative of 2012 wants to constrict the state so that common man is unable to organize legal resistance through the government against the abuse by the wealthy--ergo he tends to want a small government so that an orderly society can be maintained.