Technically yes, because half of all privately owned guns in the US are owned by 3% of people according to this CNN article. So while there are more guns than people in the US, legislation to regulate them would mostly affect a minority of the population.

That being said, you're right that a lot of the problem with gun violence has to do with external factors such as poverty and extreme nationalism. An overwhelming majority of mass shooters are male and less overwhelmingly white which hints at a problem more to do with the environments they are raised or live in. If the problem was stricly gun access, we should expect more mass shootings to have been committed by women. In addition, half of all mass shootings in the US have occured since 2000, a third of which since 2010.

The rise of mass shootings seem to coincide with the rise of more general nationalist violence moreso than increased gun access, however more guns are being manufactured now than ever. I think the problem that needs addressed more is the public perception and marketing around guns and gun culture, because the past couple decades have seen people own guns more for the "tough guy" fake masculinity reasons rather than actual practicality. For further evidence to back myself up, pickup truck sales have risen in a similar way. Pickup trucks are marketed in almost the same way minus the whole potentially killing people part, not that they haven't also been used in mass violence though.

A lot of gun regulation tends to target poor people too, intentionally or not. Tax stamps, fees and mandatory wait times assume someone has the money and ability to take time off to acquire a gun, and wealthy people (the ones who already own most guns) have both. Making it harder for poor people, who are disproportionately black, to arm themselves in a time where racist violence is hitting record highs and stories about police brutality hit front pages every week at least, is unfair.