In order to put the European exploration and colonization of the Americas into perspective, we have to understand what was going on in Europe.
This is a thumbnail view of the history of Europe, with a lot of details and important events omitted. But that's always a problem with the study of history: there's no way to tell the entire story, all of the important details, without taking a master class in the subject. At best all you get are the highlights; we used to call this "name and dates" and it omits too much of what's important and what's interesting.
As an example of the problem, take the US Civil War. You could write a fairly decent 10-page essay, touching on the major events and figures of the war, without getting bogged down in the details. You can also do a 1,000-page book on a single battle and still have to omit a lot of the details of the battle. How much information do you need to understand what is going on while seeing the big picture and the smaller details?
In order to understand the exploration and colonization of America, we need to understand what was happening in Europe during the 1490’s. To understand Europe in the 1490’s, we need to start 1,000 years earlier with the fall of the Roman Empire in 476 CE. To understand why the fall of the Roman Empire was such a important event, we have to know something about the Roman Empire.
The Roman Empire lasted 1,000 years. At its height it stretched from the border between England and Scotland in the north, to India in the south. It covered most of Europe from Spain to the Baltic States. The Roman Empire also covered all of the lands surrounding the Mediterranean Sea.
For the Romans, civilization ended at the borders of the Empire. This is a bit odd, because the Romans had trade routes to China, India, and to the major African societies south of the Sahara Desert. But in our very simplified view of the Roman Empire, there were Romans and everyone else were barbarians.
The Roman Empire started out as a kingdom on the Italian Peninsula that mostly consisted of the City of Rome and the farmlands surrounding it. The kingdom gave way to a Republic in which a Senate elected by males who owned land or had wealth comprised the electorate. Once established, the Roman Senate never entirely disappeared, but its authority would greatly diminish over time.
Like most city-states on the Mediterranean, Rome was sustained by trade. The City of Rome was situated in between the major city-states of Greece (which included Athens, Sparta, and Troy), the smaller city-states of the Iberian Peninsula (now Spain), and and those of southern Gaul (now France). The City of Rome had the advantage of its central location and became a major port of call and trading center.
Because of trade, Rome became a cultural hub. Because it became a cultural hub, it grew in size—to the point to where the farmlands surrounding the City of Rome could no longer feed its population (farmland was converted into housing as the city grew, so farms constantly had to be established further from the urban center), and, eventually, Rome had to rely extensively on trade in order to feed its ever growing population.
When Rome was founded, it was the Greeks who were the major power in the Mediterranean, on land and on the sea. The Greek city-states had colonies on the Italian Peninsula and on the islands close to the peninsula. But the Greeks had suffered greatly in several wars with Assyria for control of Asia Minor, as well as wars between the Greek city-states (mostly between Athens and Sparta) for control of Peloponnesian peninsula.
Romans developed an army and navy to protect its trade routes, both on land and across the Mediterranean Sea. It wasn't long before the Romans went to war against the Greeks who were greatly weakened from a long string of wars, and who were but a shadow of their former glory.
Rome conquered the Greek city-states and acquired the territory of the empire established by Alexander the Great. This made Rome the dominant power in the Mediterranean. Thereafter, Rome conquered Gaul, the Iberian Peninsula and North Africa. During this time the Roman army and navy became the dominant forces in Roman civilization.
Civil wars became a frequent occurrence as the power of the Senate ebbed and flowed. Finally, Julius Caesar, a Roman general fighting in Gaul, marched his troops to the City of Rome and defeated a rival general, Pompey, and established himself as the Dictator of Rome in 49 BCE. His nephew and adopted son, Augustus Caesar, went on to established the Roman Empire.
Under Emperor Augustus and his successors, the Roman Empire continued to grow. Rome conquered Gaul, Iberia, most of Germania (Germany), and Britannia (England).
In 476, when Germanic barbarians invaded the City of Rome and ended the Western Roman Empire, the Empire consisted of Europe from the Atlantic Ocean to the Rhine River, Britannia from Hadrian’s Wall to the English Channel, all of the lands surrounding the Mediterranean Sea, the entire Middle East, and all of North Africa.
After the fall of the Western Roman Empire, the Eastern Roman Empire continued to exist with its capital at Constantinople (Istanbul), in what is now Turkey. While the Roman Empire ceased to exist in western Europe, the Empire continued to exist in Greece, the Middle East and North Africa; lands that would become the Ottoman Empire. Eventually, the Ottoman Empire would include Iberia, the southern part of Gaul, and parts of the Italian peninsula.
The thing to remember is until 476 the Roman Empire, and thus all of Europe, had one form of government—a republic that elected a greatly weakened Senate with an Emperor who generally ruled by decree; one state religion that was generally tolerant of other religions, until Constantine made Christianity the state religion; one set of laws—the Julian Code; one calendar—the Julian calendar; and one army and navy that protected everyone. In the Roman Empire, a person could be born to a freed slave and rise up to become emperor, as Emperor Pertinax did in 193.
Yes, there were many problems such as slavery, little social mobility in the later years of the empire, women had very few rights, and there was nearly constant war. But citizens of the Empire generally enjoyed many basic rights and due process of law that wasn’t provided by other governments at the time. Roman citizens generally enjoyed a decent standard of living for the time. And, while the Romans could be very intolerant towards people who were not citizens, there was little bias or discrimination towards other Roman citizens based upon ethnic or cultural differences.