American is not seen as promoting human rights, and to infer all immigrants are good is naive, hate to get off my porch about this. sits back down on rocking chair whistling “I Wish I was In Dixie” and widdling a hangman with the noose almost finished, just a few more threads
Japan and Korea have almost no immigration and abysmally low birth rates. Your arguments don't really hold water. Having children is actually more of a burden on the state, as those kids need schools, (in most western countries publicly funded) healthcare, etc. Taking in a healthy immigrant at 20 is better almost all round from a purely economic point of view.
And immigration doesn't suppress wages any more or less than having tons of kids would over the long term. A person "taking" a job is still a taking a person whether they were born or immigrated. This is ignoring the fact that more people over time enlarge the economy and opportunity in it. Would the United States be a better country today if it didn't accept the mass immigration from Italy, Ireland, and Eastern Europe between 1850-1914 and had 1/4 the population?
The US is unique (or maybe there are a handful of others, I don't know) in its ability to welcome immigrants who, within two generations, largely see themselves as Americans first and not as the identity of their grandparents. American identity politics has eroded this somewhat but it is still largely true, for example, that grandchildren of immigrants will usually have a very poor grasp of their grandparents' native languages.