cristopher colombus was a portuguese explorer, funded by the spanish king ferdanan and queen isabella. All of their resources came from the spanish government. CC (christopher colombus, or Cristobal Colon his real name) discovered central and south america first (hoduras i think) and from there, when the spanish government learned of the land, which was inhabited by mayan and mapuche indians (as well as others) spanish troops came to settle the land and set up colonies, and take advantage of the lands minerals (gold, coal, diamonds, everything) and other resources.
the original inhabitants of central and south america as well as mexico in north america were indians, mayan, incan, aztec, mapuche, etc) and those dialects were the languages spoken. Spanish was only introduced through the spaniards.
These languages still exist today. There are many latino american people who speak both spanish and the ancient dialects of their ancestors, and some even live in remote areas where these indian dialects are prevalent and dominant.
there exists so many dialects of spanish due to the mixing of the cultures and languages of the original inhabitants and the spaniards. That is also why the south american people tend to have darker skin, dark hair and dark eyes, from indian ancestory.
hope this helps