You have forgotten a few things.

An "alien invader" isn't necessairly another country. I believe the legal term might be "home invasion". Individual weapons used by the military and police are commonly used by criminals. That being said, why would you restrict me - the law abiding citizen - from being equally armed to defend myself?

Your comment that "we strive" is a useless issue. We can "strive" all we want - but that's a far cry from actually having the outcome one desires.

The concept "it is the government's responsibility to do for the people what they cannot do for themselves". You can add to that "what the people won't do for themselves". Interesting and debatable concept as to exactly how far a government should go. And, as always, it depends on who is running the government. :)

As far as fighting against an adversary with a greater arsenal, I suggest you study history just a bit. Has happened numerous times.

“Neither the Constitution, nor state law, impose a general duty upon police officers or other governmental officials to protect individual persons from harm — even when they know the harm will occur,” said Darren L. Hutchinson, a professor and associate dean at the University of Florida School of Law. “Police can watch someone attack you, refuse to intervene and not violate the Constitution.”

The Supreme Court has repeatedly held that the government has only a duty to protect persons who are “in custody,” he pointed out.

https://mises.org/power-market/police-have-no-duty-protect-you-federal-court-affirms-yet-again

Zimmerman was more or less hispanic,and I think a little bit Jewish.In any event he was acting in a neighbor Hood watch capacity.He legally had no justification for accosting (Trevan) the youth whom was murdered.I , having acted in a similar law enforcement capacity know the rules of engagement regarding such incidents.Had not Zimmerman had the type of personality flaw I alluded about in an earlier post(one of those right wing lunatics) he well may not have confronted Trevan ; had not he had a weapon.To substantiate my theory about his right wing cowardness,he was the bigger man,he was the stronger more maturer man,and still knowing he had a gun ,he elected to use it- after the police told him to abort-also ,were he not psychologically flawed , and carrying a weapon he wouldn't have acted on a compulsion to prove his man hood after being humiliated by a young boy.He probably would have followed police orders and aborted.This is why most police departments do not agree with the current conceal and carry law.His life wouldn't have been in Jeopardy were he not a personality flawed,overzealous, right wing, feelings of great inadequatcy loony.

It has been a long time, but I remember Travon, allegedly, hopped the fence of a gated community, was wandering around and looking at the houses. I understand that he was looking for a specific address and was lost. He was acting suspiciously and Zimmerman was part of the neighborhood watch. There were mistakes made by both parties. Zimmerman should have just followed and reported to the police. Travon should have kept his temper and not forced a physical confrontation with Zimmerman. Zimmerman should not have got out of his car and allowed things to escalate.
The media did its part in blowing things up more after the fact. They kept showing an old picture of Travon giving the impression that he was a smaller kid. In reality he was a big guy and it was believable that Zimmerman was in fear for his safety.
Unfortunately, too many tragedies are the result of many mistakes on all sides. We don't know everything that the jury heard. We can only hope that they made the right decision based on the facts presented to them. It doesn't always work out that way. All we can do is to do our best to see that justice is done.