first things first.
Magneto is Jewish and a survivor of ww2. He "died" under mysterious circumstances in the name of mutant rights in 1969 and hasn't been seen since (because that is a gun you can only use once and you better not miss). He is a legend that both the good and the bad mutants use to cry never again and a boogyman by human supremcists.
Professor Xavier has been there the entire time and has been doing selective mind wipes to hide them from the world. His gifted students are essentially running damage control to blunt this.
But sooner or later somebody messes up and the current Avengers get a whiff and believe Magneto is alive and he's staying at the Xavier Mansion.
This attack on the school goes badly for both sides and wakes up the world to the mutant threat on a level that causes the hysteria and forces the x-men from the shadows to the limelight.
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and I'd pick the following team
Cyclops: Changing his ethnicity to 1st nations, but still keeping him the whitest guy you know really will hit a cord with a lot of people. A man who has had history replaced with mutant...sound familiar?
Storm: At one point being the poster child of the marvel universe, it's time the african weather goddess with the deadpan comedy act fullfills her role as somebody you really don't want to cheese off.
Rogue: Captain Marvel needs her nemesis and this fight is how Rogue becomes classic rogue. Captain Marvel will get back her powers and making their relationship seriously complicated.
Beast: The big blue furry genius ogre, actually joins up as an avenger before all this and is the conflicted member of the team and acting as a the voice of reason between the two groups as both consider him a traitor for trying.
Quicksilver: You remember Ralph Boner? Well it looks like that was a temporary identity created by Charles Xavier to keep his cover. Peter Maximoff lives and he gets a speed montage to "why can't we be friends"
The kids: I'd be okay with either being the point of view character whom get to witness their comfortable life get ripped away: Jubilee or Kitty Pryde. Both have their pros and cons and if you can figure out a way for both, I kind of want them on the young advengers in some future movie.
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Colossus is with Deadpool because honestly it's the best he's ever been used and so puting in a bit of pathos when he finds out what his sister Magik has been through.
Wolverine gets his own movie and I'd like him stalking for a few movies before revealing him to the world.
and Magneto never was at the school above because as started before, he really needs his own movie. Although if he does get put in, I really want Michael Xavier at the academy as an old man taking care of his people and generally given up on violence...at least until the Avengers louse it up.