spiritually speaking, how do immigrants benefit the economy?

As any working individual they pay taxes and support local businesses.In case when their jobs are outsourced to their home-countries(and this is unavoidable in global economy), they will do the same job for less money, which will affect american wages even worse and none of their salary will contribute to the US.If we are talking about legal ones, they are usually are the smartest and most able among their peers(otherwise they won't make it to developed countries), so they will enrich nation with smart and gifted children, when their former country is left with less able people and their also not able kids.

They do work most citizens are unwilling to do at wages that keep costs down. They contribute far more in taxes than they receive in benefits.

A lot of immigrants start big corporations in the USA

It was a chinese venture capitalist who funded a big part of the railroads. on the flip side of chinese workers who built it.

the state of california alone takes a net loss of about 50,000 dollars per illegal immigrant over their lifetime. whoever told you they benefit the economy is full of it.

it depends of their jobs, some works in farms