This bug took place in a standard Superflat world in a naturally generated village.

This bug is tricky to explain. Basically Villager AI is a bit wonky, some Villagers getting stuck in the doorways and just standing there, or Villagers queueing up near the steps to a door, as well as standing there awkwardly before dashing off to their next destination. (I believe there was an issue with AI calculations with Zombies similar to this)

TL;DR: Wonky villager AI!

Good Luck!