When was the last time the Republican nominee was arguably more left-leaning than the Democratic one

[Alcibiades]

1956

Exceptionally bad take.  Even if you insist on putting civil rights on a left/right scale as you clearly do, there are a plethora of other issues to consider.

This is clearly the only reasonable way to view the issue. The real question is why you are so insistent on putting 19th century issues of religion/morality on a 21st century spectrum.

Stop trying to make Protestant supremacism seem woke. It's not woke.

1892, 1904, and 1924 are all defensible answers to this question. 1904 is probably the best one. 1952, 1956, 1912, and especially 1948 and 1976 are all terrible answers, with 1912 as probably the best of a bad lot.

That 1924 is a possible answer really speaks to just how conservative John Davis was, rather than any progressivism on Silent Cal’s part. Although, I suppose the latter did have a surprisingly liberal attitude on civil rights (not just towards African Americans, but also Native Americans in particular).

[Alcibiades]

Ford was probably more culturally liberal than Carter, the same might've also been true of Dewey compared to Truman.

In what sense? You seem to be equating cultural liberalism with being more upper class.

Ford was not really more upper class than Carter, though, despite their respective images. In fact, they both came from remarkably similar backgrounds; both their fathers (or adoptive father, in Ford’s case) were upwardly mobile, enterprising businessmen from humble backgrounds who took a hit during the Depression before becoming genuinely affluent local civic notables later in life.