“Protectionism” literally means we, as a nation, protect our national interests. It is one more word that has been twisted to make people think it’s a bad thing, like “entitlement” (the things we are entitled to as citizens in a democracy) or “welfare” (people in a democracy making each others’ lives better.)
“Trade” is about competitive advantages. It used to mean one region can grow bananas and another can grow corn, and by trading they each end up with both bananas and corn in their kitchens. (Good.) Today, though, it means authoritarian governments have the “competitive advantage” of allowing slavery and pollution so their factories can make things for less. So (the executives of) big corporations move production there, then squeeze the remaining workforce here with threats to move their jobs as well if they won’t lower their standard of living. (Bad.) All the gains of that “trade” are passed to a few already-wealthy owners and managers of that means of production. They use some of the gains to influence our laws to allow them to do this.
A democracy obviously would consider its people’s standard of living an interest worth “protecting” and would never allow businesses to influence lawmaking.
Trade can be done a different way but that requires democratic governance. Economists (used to) tell us that society gained from trade because making the economy more “efficient” by moving production to lower-cost regions frees up resources, providing increased investment and general prosperity; better infrastructure, higher pay and more free time for everyone in the society. And the production moved to the lower pay area means jobs and investment there, so they also move up that same ladder to increased investment and prosperity. That assumption depended on viewing society as liberal democracies capable of making and enforcing rules that would pass these gains on to everyone.
The failure of our country to maintain itself as a democracy has resulted in the allowance of trade with slavers and polluters, resulting in the extreme inequality we see. Thereby enabling further squeezing of workers and environment here. It also incentivizes authoritarian governments to allow slavery and pollution.
The solution to this, and so many other problems, is, of course, to remove the influence of money from our political system.