> we live in a global market,
Treating local businesses preferentially does not mean abolishing international trade. Just look at China, or US agricultural subsidies, or tariffs, or countless other examples.
> Immigrants help Countries they move to
Countries, perhaps, but what about the local people? Don't they compete for the same jobs, driving down wages? Vote and take advantage of common resources (drinking water, arable land, existing infrastructure, etc.), reducing the political and economic capital of the locals? Encourage policies for more immigration, instead of policies that would encourage parenthood? Won't immigrants look out for their own interests more than for those of the local population?
Let me rephrase that last question - is racism real?
> Immigrants [...] are the only reason why the US does not have an aging population
It's a sick society indeed that can't even sustain its own population. And instead of improving itself, it makes up the shortfall with immigration. Do you really believe immigration is the only way to sustain population levels? Why can other countries manage without?