If Americans start building their own cars, phones, and computers who is going to fill the jobs these workers quit? Do you think unemployment might go down a bit? Manufacturing is a wealth creating process. Welfare and service jobs only move money from one person to another. Manufacturing also has a tail. All the things that support the process have to be provided. Things like large buildings, raw materials, security services.
The US has a very large economy, our exports are a fraction of our imports. Much of what we export has very little labor involved, mostly raw materials and intellectual property. These do not exclusively go to China so they would be on the very short end of a trade war.
Most countries do not have the tax collecting structure or individual wealth the US has. High taxes on imported goods and fuels are for revenue generation, not protection of domestic production.