From 2013, but new to me, Max Gladstone makes some close observations regarding the odd world of Episodes 1-6.
The title card tells us that the story takes place long time ago, in a galaxy far, far away. So the characters aren't actually human or even necessarily from a human-like society, they're just played by human actors.
What can we learn about the creatures true nature from studying the first six movies?
I think a few important context clues present a very different picture of the dominant race of the Original Trilogy.
Gender is the most important clue. The Original Trilogy has a shortage of women when considered by the standards of a two-sexed mammalian species. Leia is the most prominent female, and the only one to feature in all three movies. Aunt Beru and Mon Mothma also have named speaking roles. Aside from these three, I can't think of another definitely-female-definitely-'human' in the series. In RotJ Leia describes her mother, who is obviously a queen. These females all possess at least local political and social authority.
Family is a second important clue—or, rather, the absence of family. With one notable exception, people in the series don't talk much about parentage. No non-Force sensitive male ever describes his family, if I recall correctly. Han, Lando, Wedge, Biggs, Tarkin, Dodonna, and so forth, all might as well have sprung from the brows of their ships. In six+hours of film about war, I would expect to see someone to drop at least a single reference to parents of some sort. The lack of strong family ties suggests that parenting relationships are much less close for most GFFA 'humans' than for Sol 3 humans—which in turn suggests large brood sizes, short gestation periods, young ages of maturity, or all of the above.
So we're looking for an organism with large brood sizes, young ages of maturity, short gestation periods, and relatively few fertile females who naturally assume positions of social and organizational authority.
Here is my modest theory: the GFFA's 'humans' are in fact sentient hive insects, organized around a single queen, a handful of fertile males, and a horde of infertile female soldiers. For parsimony's sake, let's assume that Force sensitivity in this species is possessed by fertile males and females, and that male actors used to represent non-Force sensitive characters are actually representing infertile females.
As he observes, understanding the "humans" to actually be hive insects gives new meaning to the use of clones, obsession with Death Stars, and desire to exterminate the younglings.