Post-WW2 was a unique time when the US emerged as the strongest economy with a solid industrial base, technological superiority and skilled workers that allowed it to leapfrog and stay ahead of the rest of the world in terms of worker output, productivity and wages.
Since then, the rest of the world, particularly Asia has caught up while the industrial base, education levels and skills of the average American worker hasn't grown by as much. In addition, women entered the workforce in major numbers in the 60s and 70s, so even for service jobs and other jobs that can only be done locally, there are now twice as many workers.
There's very little reason to hire a US worker when someone on the other side of the world can do the same job at the same or higher quality level at a lower cost structure. So, most US jobs are now in service sectors (e.g. food, retail, hospitality) that are low productivity, trades (e.g construction) that require local workers or in some niche sectors (govt, security) that aren't competing with external talent. The sectors where there have been high wage growth (e.g doctors, SW engineers) are either highly regulated or sufficiently new that they still not affected by global competition.
To change this, you can either upgrade the skills of your workforce or set up artificial barriers. The former high lag activity (i.e takes years to retrain your workforce)and there is often a cultural bias against STEM in the US. The latter helps in the short term but ultimately renders your economy uncompetitive (see EU economies that have seen their dominance shrink over the last 20 years)