One of the major forces behind the revolutions in Latin America was the force of Enlightenment ideas. These ideas, of course, came from Europe, but then spread to Latin America and helped to inspire rebellions there.
For example, Simon Bolivar was an avid reader of Enlightenment thinkers. He believed in such things as the idea that science and reason could explain and should determine human actions. This led him and others like him to believe that monarchy was not the best form of government. It also led them to think that there was no real reason why people born in Spain should rule over those born in Latin America -- this did not seem logical or reasonable.
Because of ideas like these (which also helped cause the American Revolution) Bolivar and other liberators rebelled against Spain.