The economists love to say that trade is great for everyone.
You are correct. Economists do love to say that trade is great for everyone. The reason that economists love to say that trade is great for everyone is because it's true, and economists love to say true things. (Exception: exporters who face stiffer competition from foreign suppliers.)
But they assume that all parties have an equal amount of advantages and disadvantages.
What! Nothing could be further from the truth! Economists would never say that because they love avoiding saying untrue things.
There is this illusion of comparative advantage.
Illusion! It's a mathematical near-certainty. The only way that two countries could have no comparative advantage would be if the productivity of First Country divided by the productivity of Second Country were the same ratio for every product that either of them makes.
But at least with the US we are making trade deals for the sole purpose of businesses lowering their costs to boost profits and make their shareholders richer and their CEOs even richer; while we little people lose opportunities and jobs and stagnant wages.
We do make trade deals so that businesses can lower their costs, but that's not the sole purpose. It's also so that consumers can buy things at lower prices. People do lose opportunities and jobs when they are employed at making things that can be made more cheaply elsewhere, but they gain jobs when they are employed at making things that can be made more cheaply here. The neat thing about comparative advantage is that the latter must exist.
Protectionism? Absolutely not!
Protectionism? Ubiquitous! Exactly how much can be found here
What we need is a business environment like Germany's where government, business and labor all work together for society's overall prosperity.
What you need to do is give me all of your money and all of your possessions and, for a nominal fee that I'll determine at my sole discretion, I'll make sure that it's used to best effect.
In the US, labor needs much more power (unions) and business needs to be taken down a few notches.
What we need is for the government to have far less power. If they had, there there would be no incentives for business to lobby them for exclusive advantages for themselves. What we need is for labor to have exactly as much power as businesses. If businesses can't have a monopoly on goods, then labor shouldn't have a monopoly on services.