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"The ends justify the means" is certainly a valid metric by which to judge things, but an honest application of it leads one to conclusions such as "Mao Zedong was the greatest humanitarian to have ever lived" (as seen here: https://i.imgur.com/3QUXVi3.jpeg).
It's valid to ask a similar question about the Americas. What would life be like for people today? It's probable that the Aztecs or their descendants would have taken over the Americans, since they were by far the most technologically superior. Would they have evolved into a prosperous industrialized society today?
You seem to be saying that colonialism advanced society even for the oppressed, but the causality of history is complicated. As far as we know, you may as well say that the extinction of the dinosaurs as it happened was essential for human proliferation. Maybe the dinosaurs would've gone extinct at some point, or diminished greatly, or maybe the dinosaurs and humans would coexist. Just because a somewhat plausible scenario presents itself does not mean it is compelling. You have brought up counterfactuals, so use your imagination seriously, instead of taking the easy way out. If you have a motivating belief on the matter, it is untoward to speak as if you are unbiased and objective.
So your theory is that civilizations are the way they are because of exogenous rather than endogenous factors? That seems difficult to reconcile with the historical record. Your viewpoint just begs the question. For example, why was Europe in a position to colonize the Americas in the first place? Why weren’t the Spanish greeted by Aztecs with swords and guns?
Why indeed was Europe technologically advanced? Why were the Americas not so much? Resources are one factor, which is why obtaining resources from other lands is valuable. But the main impetus for advancement surely isn't based on one's "skill in advancing". Most people could be trained to fix cars, if desired. Also, Rome fell, but people now live where Rome was with far greater technology. I posit that, if the indigenous peoples of the Americas were given the desire to advance to the level of Europeans, the resources to do so, and time, similar advancement would arise.
I have provided as many facts for my argument as you have for yours.
After contact there were waves of mass die-off of people throughout the Americas due to disease brought from Eurasia: are we positing that those deaths still occurred? Because they were extraordinarily destabilizing. For example, if we hypothetically imagine that the balance of disease severity was the other way around and 90% of the population of Eurasia was wiped out over a century in several waves of horrific pandemics, then history would look quite different indeed, and it's all but impossible to predict precisely how.
European states other than Spain also did horrific atrocities in their conquests and colonial projects. Are we positing that we just replace Spanish kingdom(s) with some alternative European monarchies? Or are we imagining a situation in which peoples of the Americas retained some autonomy?
And, again, take that "rule" to its logical conclusion: How many people will inhabit the Earth after a while, and under what conditions will they live?