What are the main commercial, scientific, and political transformations of Europe between 1450 and 1600?
The so-called "commercial revolution" partially resulting from the massive influx of bullion from Central and South America was a major change. It weakened the control that landlords had over tenants, that masters had over journeymen, and, by injecting a massive amount of wealth into the European markets, it opened the way for that wealth to be employed as capital in joint-stock ventures and other investments. This was a fundamental economic transformation.
A major purely scientific event that led to a change in worldview for many educated Europeans was the publication of Nicolaus Copernicus's De Revolutionibus in 1543. This work posited that the universe was in fact heliocentric (meaning the sun was at the center of the universe) rather than geocentric (earth-centered.) If you consider technology under the heading of science, then certainly the development of the moveable type printing press by Johannes Gutenberg in the 1450s was perhaps the most important event of the period. The availability of inexpensive print material was a major development and change in European society.
Probably the most important political changes were also religious in nature, as there was no distinction between the two in early modern Europe. The Reformation, which began with Martin Luther's official challenge to church doctrine in 1517, had dramatic ramifications that eventually contributed to war within the Holy Roman Empire and elsewhere, including the destructive wars between Catholics and Huguenots in France.