This film was made to compete with the Tarantino genre. Technically great, it is redundant, a copy of already bad style. True art is not competitive. It stands as itself alone, on its own merits.
The otherwise beautiful film was spoiled by the last 30 minutes of unnecessary gruesome violence. More productive endings include: 1) admissions of error were made causing positive, cathartic resolution, or, 2) a more humorous ending where additional families in additional sub-levels are found, turning this into a marvel when they all come above ground to tell their stories in the light.
I am disappointed with Cannes.