Not as much as you'd think. D&D's conception of elves, dwarves, and halflings was straight out of Tolkien, and...that was very nearly it as far as really unique

Not as much as you'd think. D&D's conception of elves, dwarves, and halflings was straight out of Tolkien, and...that was very nearly it as far as really unique elements (barring a few monster names and specific magic items, out of hundreds). Those three races are highly visible but kinda superficial. The Howard/Burroughs/Vance/Moorcock/etc. style of swords-and-sorcery/murderhoboism is a lot more deeply baked in.