First of all, this film is about parallel universes, everyone will make infinite choices in an infinite universe every moment, and the scenes depicted in the movie are just one of their choices. The end of the film also describes what it would be like for them to make an alternative choice. If there is meaning, I think the author is talking about the importance of faith to a person, when the faith is lost, it goes into a dead end, into a bad cosmic space, and age affects people's beliefs, and when you are young, you can always find faith, such as a dead brother or sister, when you are old, you lose the belief in living, eat and die.
The first paragraph: an accident on the highway caused the death of his daughter/sister, the father blamed himself for falling into a cycle and forgot his own heart, eventually quarreled and divorced and committed suicide, the son blamed himself but was actively faced after being enlightened by his father;
The second paragraph: The son grew up to become a policeman, accidentally shot his brother in the stairs and died, the police blamed themselves into a cycle and forgot their own intentions, and finally found that their wives cheated and killed and went to jail to end their lives, and the younger brother blamed himself but was inspired by his brother to actively face the repentance and then marry and have a happy life.
In the film, the younger brother in the closed stairwell, 35 years of serious life, corresponding to the real brother in the 35 years of time to have a happy life, the end of the film reality of the brother in the library to meet the right person to marry and have children just confirmed, if the brother into the elevator, because of his own bees accidentally caused death, this accident will make the reality of their own accidents and guilt, so into the elevator trapped in the corridor for 35 years is the 35 years of atonement time after the accident, corresponding to the real life because of the accident caused by the atonement.
And the police in the stairwell is like this, the previous identity is the little boy trapped in the road serious life, so in the time of 35 years, the real life of their own marriage and children happy life, but he walked into the police car, it means that later accidentally injured the brother's brother, so trapped in the stairwell for 35 years to atone for his life, corresponding to the reality of the police found his wife's mistress and shot him to cause him to go to prison for 35 years and die. The conclusion is that the first 35 years of serious life and happiness, the last 35 years of atonement for various accidents, corresponding to the 35 years of serious life of the police on the highway and the 35 years of atonement in the stairwell.
In fact, the only way to cut off this cycle is to continue to live in the current unexpected space, do not take the elevator to leave, and do not get into the police car. However, if you don't get on the police car, you should continue to be trapped there and continue to spend the rest of your life in the enclosed space, rather than getting on the police car, after all, if you get on the police car, you will go to an unknown place, at least with the hope of leaving.
In short, there are more cycles behind the movie, from the son in the road (the first half of the young life) to the police (the second half of the middle life), people face the setbacks and mistakes in life, the way they cope determines the subsequent life, if you can always stick to the original positive face, then you can harvest happiness (the first half of life can usually do it), if you give up on yourself, then it will only be more tragic in the end. Each self-blaming character in the story does well in the first half of his life and collapses in the second half of his life. Therefore, the focus is not on the first half of life, but on the second half of life, when encountering setbacks, we must remember the original heart of our youth, and deal with the mentality of our youth in order to truly get out of the predicament.