Ironically, B/X's lack of emphasis on history and characterization makes it much easier to get roleplaying. You're not Dark McBroody, tiefling rogue with 4 pages of backstory at level 1. You're a guy with a dagger, randomly-generated stats, and zero common sense. The character develops as the game goes on.
And expendable at early levels. Thats the real filter.
W/o masses of skills and rules, you can roll up a character quickly. And if he survives, your characters 'character' will evolve organically. You roll up a dwarf fighter. He has a big axe. His entire backstory is "left his home to find enough money to pay a brideprice"
He survives the deathtrap that is levels 1 and 2.
During play, you start naming your axes after the first big foe they kill.
You decide your fighter is creeped out by giant spiders
Your fighter takes trophies from fallen foes.
You fought so many fucking mongrelmen, you really really hate them.
After several desperate situations, he develops a real friendship with the ranger. They become bros.
He clears out a small tower full of bugbears, decides he likes it and moves in with his ranger buddy.
etc etc.
All organically evolved during play. And if he dies during those early levels? Oh well. you just roll up something new because it takes 5 minutes to create a new character.