You want a correlation? Among developed countries: 1st in guns per capita (by a lot), 1st in murder rate (by a lot too).
I guess your second point is that more ethnicity mean more crime? Europe is about as culturally homogeneous as the US, as for ethnicity, some EU country have even more diversity than the US, some less, so it most definitely is a fair comparison. The US actually isn't a particularly ethnically diverse place by developed world standards, it's right there in the middle (Canada is more diverse for example):
Then about crime in general, a lot of EU countries have more crime than the US (France for example), yet a much lower homicide rate, so that's not a good argument either.
Onto the next one: single parenting. The US' might have the highest share of single parent homes in comparable countries, but not by far (23% in the US vs. 21% in the UK and 18% in France, yet they have a much lower homicide rate), so it's comparable, therefore that doesn't explain it either.
Not sure how Singapore is relevant to the discussion, because again, we're looking at countries with comparable systems, but since you want to go there: EU countries achieve their much lower homicide rate while having an arguably much laxer penal system. Taking France as an example again, crime higher than the US, incarceration rate much, much lower (119 vs 629). Looks like despite being super easy on crime, France still manages to have an homicide rate 5 times lower than the US.
And lastly regarding your extremely short-sighted question. Sure, gun ownership prevents some anecdotal crimes, no one is arguing against that, but all the data shows that little crime it probably prevents is far outweighed by the homicides it facilitates, that's the entire argument: Guns create more problems than they solve.
That's why it's tough to take anything you say seriously, again, you just regurgitate whatever talking point you heard in a source favorable to your desired viewpoint without looking into it any further, you're not capable of thinking critically.
For the record I don't even think we should ban guns, I'd simply be in favor of a licence and a waiting period, that's all (which btw is the model in most of the EU, guns aren't banned altogether there, law abiding citizens can still get guns, they just have to jump through a few hoops to make sure they're responsible gun owners, which I think is just common sense)