The part of Iowa from which I came was populated by a massive influx of German Catholic immigrants after the civil war. When they arrived, they did not speak English and were resistant to learning. They published German language newspapers, and generally overran the white settlers who first laid claim to the area. There German Catholic culture became the culture of the area. 

This story repeats with many different immigration waives all over the country. Thus American culture is immigrant culture. There is no singular American culture. It is a patchwork of multiculturalism.

Spanish was the first European language spoken in what would become the US. America itself is named after an Italian. Colorado is a Spanish name. The list goes on. The US should at least have Spanish as an additional official language. 

Not sure what you're going on about with the stabbings and all that but it is clear that white males commit the vast majority of random mass murder in the US.