A profound aspect of Zack Snyder's overarching DC story is its analysis of what makes these characters who they are, what he often calls the "Why" of the characters, and that means delving into their altruistic feelings and motivations. These three films explore who these astounding people are through their heroism and how they respond to the challenges presented to them by the world.
This results in moments demonstrating what it means to be heroes like Superman, Batman, and Wonder Woman. These sequences display the heroism of these characters, not only in how they respond to these challenges but in how they overcome their own selves to achieve these ideals in their inspirational actions.
Superman Surrendering to Humanity
Clark had every reason to fear humanity's reaction to his existence. The history of the world is enough proof of that. Yet, when Zod came knocking in search of Kal-El, Clark chose to put his trust in humanity and surrendered to mankind, putting his fate in their hands. He even allowed the soldiers to cuff him, solely to make them feel more comfortable.
Technically, it was not even the last time. Amid numerous parallels to his surrender to humanity in Man of Steel, Clark later descended upon the US Capitol in Batman v Superman to answer for his conduct in the country of Nairomi. Clark's willingness to trust his adopted homeworld is just one of the many reasons why Henry Cavill's Man of Steel is the most comics-accurate version of Superman.
Wonder Woman Inspiring Kids
Being taken hostage is a traumatizing experience. In Zack Snyder's Justice League, when Wonder Woman liberated a school field trip from terrorists threatening to blow up London's Old Bailey, the first thing she did was assure them that everything was okay, switching to a higher tone of voice as she put them at ease. One girl took a moment to ask, "Can I be like you someday?"
To this, Diana replied, "You can be anything you want to be." In this universe, Barry Allen went from being a perfectly normal guy to an actual god of speed and time. With that in mind, Wonder Woman's words of wisdom to the frightened child are totally honest, as anyone in this world can be a hero. Such is the idea behind this grand, overarching story.
Batman Saving Martha
After learning Superman’s mother was also named Martha, Batman saw in him the innocence that young Bruce lost outside the theatre all those years go. Through Batman's brilliant dialogue subverting his earlier pessimism, "We've seen what promises are worth," the Caped Crusader made a promise to the man he sought to kill: "Martha won't die tonight."
Batman pulled out all the stops to save the woman onto whom he projects the memory of his own mother. Having been off the right path for most of the film in pursuit of Superman's destruction, this scene showed him once again fighting to save an innocent life, something not seen since Zod’s invasion. It is a cathartic moment of renewed heroism for the violent Dark Knight.
Clark Saving a School Bus
One average day on a Smallville school bus became a disaster when the vehicle took a tumble into a river. Using his powers publicly, Clark dragged the bus to shore, saving his schoolmates. His father mentions he had already discouraged him from using his powers in public, yet Clark prioritized the lives of other kids.
The cherry on top was Clark saving Pete Ross, who had been bullying him just minutes before. Even as a child, Superman was unambiguously heroic, and his value for human life never wavered. In the proceeding years, he never let up and preserved his secret for humanity's sake by moving from place to place -- like a ghost or a guardian angel.
Victor Helping a Struggling Mother
Victor Stone's first act of heroism after his transformation into a cyborg was helping a struggling single mother who found herself homeless after being evicted from her apartment. As she attempted to withdraw what little money she had left from her bank account at an ATM, Victor used his limitless hacking powers to give her a fortune.
It was a tear-jerking moment of kindness. This contribution showed Victor's inherent goodness could shine through his apathy. The young man's altruistic side ultimately came back in full force as he embraced his new capacity to do good in the world, and Cyborg stood side-by-side with other heroes of the world who, in one way or another, could relate to and understand him.
Batman Distracting Parademons
"Whatever you see, stick to the plan. That's why I brought you together," said Batman with a smile. He presumed these would be his last words to his crew in person. His guilt had caught up to him, and he risked almost certain death to distract as many Parademons as he possibly could, leading the swarm away in the speeding Batmobile to give the League a shot at reaching the Unity.
Superman had given his life to save the world, and Batman felt responsible for his death. To Bruce, this was his chance to atone, likely giving up his own life to keep a promise he made on Clark's grave. But the Justice League came to his aid at the last second, saving him -- and the world -- as a combined whole. No words were necessary. None of them would die that night.
Superman Destroying the World Engine
When Lois asked Clark if the terraforming effects around the World Engine would leave him vulnerable, he subverted his father's "Maybe" with his own, "Maybe, but that's not going to stop me from trying." So he flew to the Indian Ocean and fought to save humanity from a Kryptonian death machine.
In a powerful moment, Superman overcomes the atmosphere of Krypton to destroy the World Engine, saving humanity and the endangered citizens on the opposite side of the planet. Speaking of whom, even the shrewd Perry White showed his heroic side by fighting to free Jenny Jurwich from her imprisonment under rubble at risk to himself. Everyone was a hero here.
Flash Reversing Time
With absolutely no idea what might happen, how much things could go wrong, or if he would ever survive, Barry ran faster than ever before to help his teammates. In an epic sequence that evokes Superman reversing time in Superman (1978) Flash literally ran back time to bring the entire Justice League back to life.
The final emotional element of the scene is Barry’s words to his father, wanting him to know that his son really did make the best of himself. He echoed his father’s advice to make his own future, but with a twist: to make his own past too. This scene is what made him a true hero, and it will be interesting to see how the upcoming The Flash film can compare to Justice League.
Superman Taking a Nuke
In Batman v Superman, symbolically and under protest from Calvin Swanwick (Martian Manhunter), humanity made a cowardly choice to fire a nuke Superman in the hopes of saving themselves from Doomsday. Superman knew what they were doing and had no certainty of his own survival, yet he held Doomsday in place and took the rocket head-on. He never even thought twice.
Without any regard for his life, this showed just how readily Superman would endanger himself for humanity's sake. Having learned from the events of Man of Steel, he chose to make himself collateral damage rather than risk any more devastation. It was not even his only sacrifice that night.
The Death of Superman
Embodied within the symbol on Superman's chest is the belief in every person to be a force for good. After the Capitol bombing, he despaired that the real world was not compatible with the ideals he sought to live up to. "My world doesn't exist anymore." This despair was reinforced when Lex gave him an ultimatum to kill Batman lest his mother die.
Then, the brutal vigilante who sought to murder him was suddenly promising to save his mother's life. So, when he sacrificed his life to save humanity, it was not just an act of selflessness. He died as a symbolic gesture, regaining faith that there is good in this world. His sacrifice silenced hate and made humanity better with his example, defining what it means to be Superman.