Thoughts on Marxian

My thoughts on one of the logic fallacies of Marxism.
Karl Marx claims that labor is the source of output and value and thus landlords and capitalists are doing nothing but extracting workers' labor value.
But if labor is really the only source of wealth, doesn't it mean that we should always buy things that are made by hands and by zillions of hours? Won't that be a huge waste? From the class, I can assure that VALUE MATTERS (in my opinion, one of the biggest difference between econ and natural science like physics is that economics can create while physics follows law of conservation of energy.) Because I impose value on one thing, it incentivizes me to spend resources (in most occasions, money) to offset the cost it incurs during the production to get the stuff. So it's value that lets me do econ decisions.

Besides, Bastiat once in his article claims that human has an innate nature to lower the ratio of effort and good results. And i think this is the source of technology exploration and improvement. That's ABSOLUTELY self-interest. So if Marx claims that we should put labor on the top, it is actually against the evolution of human and against the trend of history. We can simply go back to 2000BC, in which all people cultivated or did hunting and gathering. There will even be full employment!!!

I heard that China now imposes anti-dumping duty on American importing cars like GM, Benz. One of the government officials said excitedly that it will stimulate domestic automobile manufacturing. Unfortunately this is another application of broken window fallacy. Sometimes I got really confused about the policies politicians and governments make. It seems some of the governors don't understand econ principle which even an 18-year-old student can possess. It's true that government has different incentives and politicians long for spotlight headlines rather than long-term benefits for their elections and support, is political success that important?