Neither of those has shown to bring about any substantial change in gun violence rates. The obvious issue is that Boomers and older generations allowed the mass proliferation of firearms and refused to actually raise their children in close proximity. And all the "three strike rule" and mandatory minimums do is ensure there's a vastly higher incarceration rate, things don't actually get safer
Look at Fruitvale in CA - like 1/3 of the Black male adult population is either incarcerated or under state supervision and it has the time highest rates of gun violence and some of the lowest life expectancies.
All you're advocating for is a much more extreme ghetto than the one that already exists.
The mayor and the teachers have nothing to do with this - because gun violence stays, regardless of the mayor and until the federal and state governments provide vaccines for the overworked teachers, there's no good reason to send them back to get sick and die.
I agree about employment, this is the result of damn near a century of segregation in Chicago, gang culture that developed out of that segregation, austerity measures that cut mental health services, housing services, educational services, and social services - and yes, parental failure that came from that as well.
Hopelessness will do a number on the youth.
Poverty creates the conditions - you don't have to be hungry to engage in community violence.