The decline of US manufacturing tracks very closely with the decline of the highest marginal tax rate--i.e., the amount of income tax paid by the richest people on the portion of their income over the highest income tax bracket.
The highest marginal tax rate peaked in the mid-50's, and slowly declined through the 70's. Manufacturing--and therefore manufacturing jobs--continued to rise during this time, peaking in 1979, when the highest marginal tax rate was 70%--and had been for most of the decade. (Again, this is the tax paid by the richest people, on the portion of their income that is above the highest tax bracket, which in 1979 meant income over $215,400 a year, for a married couple filing jointly.)
In 1982, Regan took office, and the highest marginal tax rate plummeted to 50%.
Throughout the 80's, US manufacturing continued to decline, while the highest marginal tax rate went into freefall--bottoming out, in 1988, at 28%, before bouncing back up to the mid 30's, where it has stayed ever since.
The decline of manufacturing meant that people lost their jobs, which of course created economic hardship for them, but the decline in the highest marginal tax rate--tax breaks for the wealthy--was felt by everyone except the wealthy. There was less money to maintain infrastructure, less money for schools, less for higher education--which meant rising tuition, especially at state universities and junior colleges, which had formerly been publicly supported as affordable options. Public hospitals and clinics had to charge more, and then were swallowed up by for-profit conglomerates.
First-time homebuyer programs were cut--these were programs that gave people who were purchasing a home to live in, and did not already own and real estate, access to non-predatory mortgage lending and lower up-front costs, which meant that young people and families had a shot at putting together an offer that would be attractive to the seller, and not be immediately outbid by someone who wanted to buy the property and rent it out. These programs were done through regular banks, and nobody who used them thought of themselves as having benefited from what Regan et al. would call "a government handout," and so they gleefully kicked the ladder out from under those coming up after them.
Basically, a lot of things started to suck, right around the time that US manufacturing started to decline. And the GOP sold the American public on the idea that everything was starting to suck because of the decline of manufacturing jobs--because everybody knew about a factory that had closed and someone who had lost a job, but nobody understands how the fuck marginal tax rates work.
They said, look back at the 1950, when we had manufacturing jobs galore, (and certain groups of people knew their place), and a man could work an honest job and make enough to support a family, (and women kept to their place at home), and wasn't that great?
And what they don't tell you about those times--which were, yes, a period of unprecedented prosperity and social mobility for white American men, and by extension for white American women married to white men--is that the rich were paying 91-92% income taxes on the top slice of their income.
And the government--in the hands of people who had ridden out the Great Depression, and the very real fear that it would cause a Communist revolution here in the US--spent that money on making (white) middle-class life feel comfortable and prosperous, and on building some on-ramps for a reasonable proportion of (mostly white) poor people to work their way into that comfort and prosperity.
Anyway. Manufacturing jobs? Sure; I don't think they're integral to the process, but if they're good union jobs, with safe working conditions, job security, and a family wage, let's have them. Ditch the racism and sexism, definitely.
But the big thing is, bring back the 92% top marginal tax rate--allowing for inflation, let's say on everything over a million dollars a year.
Plow that money into schools, into parks, into colleges and universities, into healthcare; into homebuyer programs, and neighborhood revitalization, and construction of nice, affordable starter home for the burgeoning middle class. Pour some into climate research, and into workforce training for sustainable industry, into medical research to defeat this century's top killers. Hell, put a human being on Mars--as long as it's a giant leap for humankind, and not a boondoggle for Elon Musk.
That's how we make America great again. Tax the motherfucking rich.
TL:DR: People want factory jobs back because America went to shit in 1982, and the GOP convinced them that it was because of factory jobs going away, but really it was because that's when the rich stopped paying their fair share.
(Sources: Marginal tax rates, US manufacturing, tax brackets. )