I guess you do need some background information, especially because Wizards sure doesn't like spelling it out anymore.
In older editions it was assumed nearly all half-orcs were the offspring of rape, and "the blessing of Luthic" was given to make orcs fertile with nearly every other race.
The implications were clear, even more once you start diving into things like orcish society being a rigid patriarchy with a slave economy and one of Luthic's domains being not just servitude, but specifically female servitude.
In early DnD's defense, monster races were objectively, comically evil, and players were pretty heavily incentivised to pick humans (and assumed to be played by extremely nerdy guys), so it wasn't supposed to come up that much.
The fantasy was in killing the cannibal rape monsters, freeing their slaves, and not having to ask yourself "Are we the baddies doing an imperialism?" for burning down the orc village.
My dad used to play red box D&D (which I believe was the first edition ever released). Still has some manuals, which I got the chance to read.
Not only it was encouraged to play humans, it was assumed! You didn't get to pick a race, only a class. And while the classes of "elf" (think like 5e's ranger) and "dwarf" (5e's barbarian, sort of) were a thing, all of the other classes assumed for the player to be a human. You couldn't play an elf wizard: you either are an elf OR a wizard. Wild stuff, compared to some of the crazy stuff we get to do in modern D&D.
Not familiar, but from what I just read online it looks pretty similar yeah. I believe the idea behind DCC was recreating exactly that simpler old school fantasy.
Late reply, but original D&D and Holmes-book D&D came before Red Box. Not sure about OD&D, but Holmes had race-class separation. AD&D has roughly contemporaneous with red box, and had the concept of Elf Wizard.
Red box D&D (both its editions) was pretty different in a lot of ways than other editions.