We really need to talk about this scene a lot, because holy wow. The MCU movies have definitely been getting a little darker since the Avengers, but scenes like this? This is pure optimism. Tony is told he can save 4 out of 13, and then he saves all 13 of them anyway, because these people can work together and help Tony save them.
If a similar scenario had happened in the Dark Knight Saga or Man of Steel, you know damn well 9 out of those 13 people would have been dead. Hell, Bruce or Clark would have been lucky to even save the 4, because DC movies have gone down a route of unrelenting gritty realism that makes good old super heroics virtually impossible. Bruce can’t save the city without faking his own death; Clark can’t save the world without becoming a murderer.
But even in the darkest hours of the Marvel Universe, Tony Stark can damn well save 13 people plummeting to their certain death. Is it realistic? Hell no. But it was an awesome victory that both Tony and the audience needed at this point in the story, and by god it was heroic.