Nobody other than yourself is making any such claim.
American citizens and legal immigrants have a right to be in the United States, illegals do not.
Crimes committed by illegals are completely preventable, those by lawful residents are not.
Most of us on the Pro 2nd Amendment side of the argument have been working hard for decades trying to reduce crime period by focusing where we should, on the criminal class rather than attempting to do so by infringing on the rights of the law abiding and it has been working magnificently well.
Since violent crime rates peaked in the 90’s percapita lawful gun ownership has more than double. The number of people lawfully carrying over that time frame is up by more than 20 fold.
It is people like me who not only promote better school security, hardening the targets, and allowing the faculty and staff to provide an instant armed response to a school shooting, we provide them the training and resources to allow them the best chances of successfully defending themselves, their kids, their schools, to bring those incidents to an end as rapidly as possible.
Children will continue to die in mass shootings, that’s unavoidable, but what we can do is continue reducing the number of such shootings by providing effective deterrents and the most rapid response possible and in doing so also keep the casualties to a minimum.
In over 90% of such cases over 90% of the damage will be done before police can even arrive on campus much less begin to engage an active shooter. The same holds true for most locations where such shootings occur.
As for you final statement, how about instead we secure the borders and step up interior enforcement and remove the illegals before the have the opportunity to harm anyone else.
Once we’re well on the way to solving that issue we can free up even more resources to deal with the criminals who are lawfully here.