This Article by "Compassion.com emphasizes child malnourishment and poverty as well as rampant government corruption. When I observe the situation in African nations it almost resembles a neverending quiet revolution. There are many wars/conflicts in east/central Africa as I write and even if Africa has many Natural resources it still is considered "Developing". here is a piece of the article that came out to me the most:
"Poor people often lack hope for the future because they live in a lie. The lie of poverty, that is reinforced day-in and day-out is, “You don’t matter. You’re worthless.”
Whether in South Sudan, Ethiopia, Uganda or Zambia, the poor in the world's poorest countries live in hopelessness...every day, in multiple ways.
Imagine not being able to provide enough food for your children or pay for a hospital visit when a child is sick or injured. Imagine the guilt, grief, and despair.
The poor are helpless in the face of war and natural disasters. When natural disasters and conflict occur, the poor suffer the most. They are unprotected, uncared for, and unnoticed.
Overcrowded urban areas where millions of the poor live in slum conditions increase the risk of disease and increase the death toll when conflict and war erupt or an environmental disaster hits.
Poverty often causes the poor to put pressure on their environment, and in turn the environment contributes to the suffering the poor endure.
Damage to the natural environment in which the poor live increases the impact floods and other natural disasters have. But "natural disasters" are as much a result of poor government, bad infrastructure, population density, rampant population growth and unequal living conditions as anything else. Extreme poverty helps create the disaster.
Limited access to sanitation and clean water lead to poor hygiene practices and more disease, which hinder the ability of the poor to work or attend school. And when someone more powerful takes advantage of them, from withholding wages or payments to trafficking a child, the poor are unable to pursue justice, for they lack the money and connections to do so."
Meaning of "Developing"
Many people say the word "Developing" to refer to mostly African/Latin American Nations. Developing is better than using the term "Third World" which is disrespectful. Developing is when a country doesn't have enough resources to be successful but has those resources getting increased when that resource (And Health Generally) is many, it thus will be a "Developed nation".
Here is another piece that explains why Africa lives in poverty:
"One in three Africans live below the global poverty line.2 They make up 70 percent of the global poor, and their numbers are rising.2 Despite the overwhelming number of extremely poor people in Africa, the causes of poverty on the continent are no different than the causes of poverty around the world. They can be grouped into two primary categories—external or cultural factors and internal elements.
External factors include, but are not limited to:
Lack of shelter
Limited access to clean water resources
Lack of access to health care
Limited or dwindling natural resources
The internal elements that contribute to poverty are intangible and can include, >among many possibilities, deficiencies in:
When you’ve never seen someone escape a life of poverty, you have no reason to believe that escape is possible. Poverty becomes your lot in life and part of your identity.
You can’t imagine a better future because you’ve never seen one, or if you have, it’s a future for other people, not a future for someone like you.
This lack of hope keeps people in poverty even when an opportunity that could change their lives presents itself.
What Causes Poverty in Sub-saharan Africa?
While the root causes of poverty in Sub-saharan Africa are not different from the causes of poverty anywhere else, poverty has been growing in Sub-saharan Africa due to the long-term impacts of external factors like war, genocide, famine, and land availability. Unless all the factors are addressed, the cycle of poverty in Sub-saharan Africa will gain momentum and continue grow, as each component of poverty reinforces the others."
As you pointed out in your question, you are right the US is a former colony but the US was not the "Victim" of the colonization, Indigenous Americans were the victims.
Mussolini's Italy attempted to colonize Ethiopia only to meet a gradual failure. The way the Italians met the Ethiopian's with such hostility and toxicity certainly did affect their economy. Colonization does qualify as a factor.