Of Course, but the third-world has been the "third world" because of exploitation from foreign countries, and support for such exploitation by the aristocratic/capitalistic elite of such a country. To fix such a situation one needs to critique the nature of capitalism (not only reform it), get power away from the burgoise and the elite (get rid of the anti-social natures of capitalism), and reform the country, to have a socialist aspect with still some sense of capitalism and markets under strong social(ist) provisions, equality in terms of economic and social power between it's citizens, a strung public sector to help it's citizens, coming with with regulated private business, that still allows for the development of small business, but does not alow the capitalistic and economic elite to reign free.
Ok, I'm really sorry to re-hash that, but this is a simplification. Was there colonial exploitation? Yes, of course. But what was the main form of wealth in the countries of Asia and Africa back then? Spices and precious metals. The main harm the Europeans did was to confiscate a lot of the wealth storage of the countries they conquered.
But I would argue that industrialization is the main advancement of society since 1800.
You're making some great points in this thread, but you're fundamentally wrong about colonialism. Vast disruptions in populations, agriculture, trade networks, social and political structures, etc. in the various regions in order to remake these regions according to the economic, political and ideological designs of various actors in colonial projects. It's hard to know where to begin. Maybe the transportation of crops, animals, and (often forcibly) of people, across continents and oceans?
That does not mean at all that the blame for world poverty in anything remotely like a general sense can be put at the foot of colonialism, but it did have real and lasting effects, for good and certainly in a great many cases for ill. The impact has to be measured in specific historical-geographic terms.