Worldwide wealth inequality isn't as important to look at as overall worldwide poverty, which has gone down markedly over the past century. It is much preferable to be able to have running water and food despite the richest person in your country having 30 houses, over having no water or food but the richest guy only has 2 houses. In the former, inequality is higher, but the absolute pain of poverty is lower, which is a more relevant metric for human welfare.
The industrial revolution, in the 1800s, transformed England and Europe due to the incentives of the growth of industry, and the free movement of labor towards those incentives. Largely, those who worked in factories did so because the benefits/costs exceeded that of farm work. If there were no incentives to change, everyone would have stayed on the farm, preserving the agrarian status quo. Despite all the hazards, the benefit/cost was better for industrial work, largely because it paid more, the money allowing for the improvement of living conditions for those who worked in factories.
I agree that to get better working conditions has been a constant battle between the interests of the working class and capital owning class, but looking at everything through that lens ignores the whole point of work/industry in the first place, in that it produces surplus wealth, and only once that wealth is produced can societies make the decision on how that wealth is allocated. In every society that has generally followed the rule of "free market capitalism with common sense regulation and protection of private property", living standards, median wealth ownership and wages, etc. have almost universally gone up decade after decade.