The four main points, the left misses, is the counties that are being tariffed, have high tariffs and obstructions on US goods. The amount the Trump is imposing is not even equal to what they do to the US. Trump is making the playing field, closer to level. The real complaint in Washington is a level playing field makes less margin for political shakedowns, kickbacks and donations.
The second point is the left does not understand international trade at the level of importers and exporters. This is where bulk buying occurs and where factory schedules are made for many years in advance. These contracts are set for the long term, and include estimates in future tariffs, future raw materials, future labor costs, future utilities such as oil, etc. The net result is these contracts are like a large ship being turned by a small rudder of tariffs. It does not turn on a dime, but the turn is very gradual, since tariffs were already negotiated even before Trump did anything. The middle men; wholesaler and retailers, may use media deception to cash in on the faux media expectation, to raise some prices.
The third point is China and Mexico are not the only countries in the world that can make products sold in the US. Selective tariffs on certain countries, like China, makes other smaller countries better able to compete. This check and balance requires China and Mexico hold down prices, at the risk of losing future sales. Viet Nam, Indonesia and others would love to see more exports. This threat of new competitors offsets some of the turn in the large ship.
With the ship slowly turning, it makes more and more sense for US manufacturing to get ahead of the ship, and try to pick up the slack. They invest in new factories and create jobs. Trump will make it easy for the off-shore money to be brought home, with investment in new factories, a way to make money; GNP increase.