LAS VEGAS — Why do the payoffs of Captain America: Civil War ring so resoundingly, satisfy so completely and hew so true?

Because Marvel earned them. The hard way.

The 13th film in the Marvel Cinematic Universe — which is falsely billed as a Captain America film because let's face it, this is really an Avengers movie — stands firmly upon the bedrock and sediment of all 12 that came before it, trusting that its audience is up to speed and, most importantly, cares about these characters.

And not only do we care about them, we care about their relationship dynamics. Which is why Civil War works so well, hits us so squarely in the solar plexus, whips us around a full range of emotions.

In that respect, Civil War is the most humanized Marvel movie to date. In another, equally important respect, here you will find the cleanest, most infectiously watchable superhero action that modern moviemaking can afford: big, high-stakes fights with clarity you can easily track across the screen, but also narrative purpose, with wild humor beats and heavy blows that actually move the story along.

Those elements, combined with some delightful surprises — and yes, those meaty and meaningful debuts for both Black Panther and Spider-Man — give us what may be the best Marvel movie we're ever going to get.

This may just be the MCU's Empire Strikes Back.

I hope I'm wrong about this. Co-directors Anthony and Joe Russo, who came into Marvel with the surprisingly bar-raising Winter Soldier, will be expected to ratchet it up one more notch for both parts of Infinity War, Marvel's Phase 3 finale that will feature a showdown with cosmic big boss Thanos.

Those films will surely thread even more characters into the mix, including the imminently arriving Doctor Strange, the much-beloved Guardians of the Galaxy and the as-yet-uncast Captain Marvel, each of whom will play a big role in defeating Thanos, whose powers are too great for our Earth-bound heroes alone.

But for now, those heroes have become our own, and no Marvel movie to date has cast their humanity or the truths of their personalities in such sharp relief as Civil War.

No Marvel movie has cast these characters' humanity in such sharp relief

For starters, they make mistakes. Not every shot lands with precision. Not every decision is purely motivated. There are irrational, emotionally fueled actions that, as human beings, we can completely understand.

Therein lies the beating heart of Civil War, which, if you've seen any of the the marketing, you know trades on a fundamental conflict between Captain America (Chris Evans) and Iron Man (Robert Downey Jr.). Here's the beef: Tony Stark, who kicked off this cinematic universe with Iron Man in 2008, sympathizes with the growing political movement to put "enhanced" humans under the watch of a global coalition led by the United Nations. Steve Rogers, who has seen his share of governmental corruption in his 90 years or so, does not.

For the first two acts of Civil War, these two seemingly equally valid worldviews bifurcate, leading the team we love to watch working together suddenly stand apart.

Things get messy, but not so messy that we don't know why. That's because there are deep, unbreakable loyalties at play; there are secrets; there is the sting of betrayal and the scorching belly-fire of vengeance.

Ah, vengeance. Anyone who's ever been burned, sold out or stabbed in the back — and who hasn't? — will know why it leads people to do insane things.

As such, this isn't the Avengers trying to punch and problem-solve their way out of a predicament. That was fun for a couple of films, but was already getting old by the time we met Ultron. Instead, it's the Avengers' diverse array of powers, character traits, worldviews and personal baggage coming into inevitable conflict, and in a way that it at least seems they would if, you know, this stuff was real.

And it feels real. Why? Because we know these people. After a dozen films, they are like family to us.

Whereas Batman v Superman tried to build that whole clockwork all at once, Marvel risked millions and took years to painstakingly craft the case, the face, the pendulum and hands and gears, one shiny cog at a time. They earned this payoff, a Marvel film with towering emotional stakes — stakes that will have you holding your breath during the big action setpieces, involuntarily and knowingly guffawing at the jokes, dropping your jaw at the fun surprises.

There are flaws in Civil War, sure. The villain, Daniel Brühl's not-very-menacing Baron Zemo, is a minor pivot point, underdeveloped and never in costume (that will probably come later). But there may be method to this choice, which clears the runway — quite literally — for the greatest superheroes-vs.-superheroes showdown we could have possibly hoped for.

Top that, Marvel.

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