Social democracy, as a form of democratic socialism, is a great idea. The most free societies in the world embrace social democracy. Social democracy needs to be updated and reformed; a land value tax and basic income or social dividend is necessary for the society of tomorrow, so there's work to be done.
The structure of society that Thomas Jefferson, Thomas Paine, and Benjamin Franklin envisioned for America was democratic socialism or social democracy. The term "socialism" didn't exist yet, but that's an accurate description of their views. They wanted widespread distribution of ownership so that everyone had access to land and means of production, they advocated highly progressive taxation so that the wealthy would pay more than the average person (not just a greater amount of money, but a higher rate), they wanted profit-sharing enterprises so that all people could potentially own their own business or a share of the company for which they work, they wanted land to be publicly owned and the people to pay ground-rent (land value tax) in order to fund social welfare programs (most notably, a citizen's dividend to all Americans, with a higher dividend for retirees). The founding fathers were, beyond any doubt, a bunch of dyed-in-the-wool socialists. The founding fathers represent a wide array of views, but they all basically fall somewhere on the socialist spectrum.
To be conservative is to be absolutely un-American and un-patriotic. To reject socialism is to reject the ideas that America was founded on.