1590s, in reference to the horizontal and vertical lines of soldiers marching in formation, from rank (n.) in the military sense of "number of soldiers drawn up in a line abreast" (1570s) + file (n.1). Thence generalized to "common soldiers" (1796) and "common people, general body" of any group (1860).
in reference to combat or competition, "hand to hand," 1970s, Spanish, from mano "hand," from Latin manus "hand" (from PIE root *man- (2) "hand").
c. 1600, Latin, literally "to a man," from ad "to" (see ad-) + hominem, accusative of homo "man" (see homunculus). Hence, "to the interests and passions of the person." Originally an argument or appeal to the known preferences or principles of the person addressed, rather than to abstract truth or logic.
Aristotle (Topics, viii 11) remarks that it is sometimes necessary to refute the disputant rather than his position, and some medieval logicians taught that refutation was of two kinds, solutio recta and solutio ad hominem, the latter being imperfect or fallacious refutation. [Century Dictionary]
"person or thing that people hope will be very successful in the near future," 1911, originally in U.S. sporting use in reference to the quest for a white man capable of beating champion pugilist Jack Johnson.