Seven Zhou, a 32-year-old worker who assembled transmissions, lost his job last month. His paychecks had already shrunk by two-thirds because he was working fewer hours. He quit smoking to pay for food and rent, and the family is struggling to pay for the after-school English and math lessons his son needs for a chance at college.

“I do not have much education,” Mr. Zhou said. “I had hoped my child would not be like me, the bottom level of labor.”

As China transforms, many global businesses are struggling to adapt. China’s economy has matured and can no longer match the sky-high growth rates of its go-go years. The Chinese government is trying to cope with all the debt accumulated to pay for that growth. Initiatives that could juice the economy have slowed.

The rest of the world has begun to fundamentally rethink its dependence on China to make much of what the world consumes. Some within the Trump administration see China as an existential threat to core American industries like autos, much as it has come to dominate production of solar panels, steel and aluminum.