|Classic David Trampier from the 1e|
This is perhaps the strongest aspect of the 5th edition brand - that makes motions in the direction of creativity and setting variation which some earlier editions refused to. Perhaps starting in the late 80's - early 90's as TSR released setting after setting, the idea embraced in the earliest editions of the game that each table of players and Dungeon Master should create their own world (I'd argue collaboratively), was abandoned and D&D products seemed to push an orthodoxy with settings defined and each setting deadened by reams of officious petty rules and mechanics. For example, the Spelljammer boxed set (a 1989 setting about fantasy space and space faring on magical sailing ships) spends little time offering up the sorts of strange and fantastical setting ideas it's core conceit promises, glossing over some great ideas in favor of complex rules about orbits and star types that seem more appropriate to a hard sci-fi game like Universe or Traveller. 5th Edition doesn't make this mistake, or at least it hasn't yet, and while I may critique its efforts at producing adventures for their devotion to the terminally bland Forgotten Realms setting and heroic fantasy, the Dungeon Masters Guide at least suggests Dungeon Masters design settings that vary greatly and offers some rules to aid in creating settings in 'mythic fantasy' (classical antiquity/mythology), 'epic fantasy' (even more high powered and magically focused), 'wuxia', 'dark fantasy' (Ravenloft effectively), 'mystery', 'intrigue' and 'swords and sorcery'. Sometimes rules are even offered up by the Dungeon Master's Guide to suggest how to better run these different sorts of campaigns.
The last category of 5e settings, "swords and sorcery", is largely a description of how earlier editions of D&D played (or perhaps were intended to play) - at least in my experience. Informed by the novels of Vance and other 30's - 60's pulp writers, this fantasy is a bit grim, and darkly humorous with heroes that are only slightly more impressive then normal men (or less in the case of Cudgel the Clever), who largely seek their own advancement and survive mostly by luck and their wits. The world is dangerous and uncaring, and if these sorts of wandering heroes become involved in an epic quest it is only by their own decision, a curse or accident.
The Little Brown Books or "White Box" are the first edition of Dungeons & Dragons - presenting a simple and somewhat muddled set of rules that almost compels a 'swords and sorcery' style setting and game (at least as the 5th edition Dungeon Master's Guide defines swords and sorcery) because the combat mechanics are high lethality, power levels flat and the exploration rules encourage caution and the accumulation of treasure rather then seeking combat.