At bottom, it's politics. Most people in Asia, Africa, and the Middle East have a top-down, paternalistic view of government compared to western europeans and in particular Americans. So political parties who support a paternalistic government are heavily incentivized to increase immigration to gain voting power over their political rivals. It's basic math.

No, because the "United States" is the name of a country--a man-made entity--not just a label for an outline on a map. That country was made by a specific group of people, who brought over their language, culture, laws, and political philosophy. Those people were settlers and founders. The people who came into that pre-existing society are immigrants.

I'm a Bangladeshi immigrant married to an Anglo-American. Almost everything about America reflects her culture, not mine. At home, we speak the language her ancestors spoke, not mine. We're both lawyers. We deal with concepts her ancestors developed over the past 800 years, not mine. Our kids grow up learning things like individualism, which is a concept her ancestors developed, not mine. She's descended from settlers, whereas I'm an immigrant. It's like the Last Samurai, where Tom Cruise's character settles down with the Japanese woman. He's an immigrant, but she's not an immigrant--even though technically Yamato people came to Japan from the Korean peninsula: https://en.wikipedia.org/wiki/Yayoi_people.

In fact it's even starker because the United States borrows almost nothing from the Indian nations that existed on the land before it, while the Jomon people had a much larger influence on present-day Japan.

No, many people people are born in the usa, having never lived elsewhere.

The definition of native is "Being such by birth or origin.". This means that everybody born in the US are native Americans.