Within this original context for this thread and its rebuttals, Jefferson's was much more of a seminal influence than you insinuate. Not that I or any conscientious critical thinker could be entirely comfortable with this, of course, given the obvious reasons you state. Still, his influences spread and continues to pervade so deeply and broadly not just because of the Declaration of Independence, an epochal document even ahead of himself though he understood its significance and progressive intent, but because of his national character-shaping work throughout his philosophical writings (especially Notes on a State of Virginia) and politically through such measures as the Louisiana purchase. Though they did have progressive and/or meritorious intentions and effects, these are of course not things any conscientious historian critic or theorist could characterize as wholly beneficial and humane either. Their legacy has shaped our country so deeply in many complicated, interrelated ways some good some bad other neither and still more that can't be so readily diagnosable ethically or morally. In all these respects they've been woven into the fabric of the American enteprise, identity, conflict and penance, which itself as a melting pot of the world, is culminative not only of the tangles but also of the richness within the larger tapestries of world histories and character(s). More on the pragmatic level than the idealist one, FDR has had a similar impact. Wilson, as I see it, not nearly as much as these two, though some of the OP's points pertain on a less immanent level than the former two, Kennedy, or, now, Obama....

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One quick side note-- Did Jefferson himself purport the 3/5 ID? That was the Constitutional Congress which he was not a member of. Of course its really just a moot point because he did support the constitution, though it might be a stretch to imply he's the originator of that particular article and concept. In Notes on a State of Virginia he argues in detail for the freeing the slaves, though he also does personally purport considerable racist and/or racialist views there as well.

Then another note.... I can't say I respect the man either, but I don't think the OP was requesting we do that--rather, if I read it correctly, he was forming a proposition on legacies, which are different from personal respect because they are transactional and national rather than based on individual moral verdicts....