Again, I don't care who shipped the jobs or why. That's irrelevant.
Why is definitely relevant. If you don't know why jobs left the USA then you can't bring them back.
Cost of wages isn't the problem. Factory jobs actually pay well. iPhone factory workers in China earn around $750/month which seems very low... until you compare it to the average wage of $220/month in that country. US factory workers earn an average of almost $80k per year.
When you consider the production capacity per employee, the higher salary in the US isn't all that significant. Wages are $80k per year in the USA because the work they're doing is worth that much.
The real problem is a lack of skilled labour. According to Forbes, one US manufacturing company they profiled said over 70% of people hired aren't qualified for the job. They're hired anyway because an unqualified worker is better than no worker, but it highlights the real problem.
There are not enough people who want manufacturing jobs in the USA. When people really want a job, they go to school and learn the necessary skills as an investment to a life long career. When people enter a job untrained, they often see it as a temporary thing and plan to quit immediately which means it's very risky for the company to pay their salary while they learn.
China has 12,000 schools focusing exclusively on vocational skills in the manufacturing industry - with a reported 29 million students nationwide. There are less than 150 vocational schools in the USA - and a lot of those have nowhere near the thousands of students in a typical Chinese school.
Bringing manufacturing back to the USA needs to be done at an educational level. There are jobs available, there's nobody qualified to fill the jobs.