The Kree in the comics are an imperialistic race of conquerors who, at one point, had a second race that was more peaceful on their world but were wiped out because reasons. Since then, the Kree helped push along Earth's evolution by creating the Inhumans, who were abandoned only because the Supreme Intelligence (giant head possessing the collective intellect of their species) viewed the Inhumans as a threat. Ronan himself serves for the betterment of his people and is not just purely evil. He's not below standing beside Thor, just another big man with a good hammer, if it suits his purposes. In a recent storyline, after the Avengers went offworld to fight off an invasion of highly advanced "builders"- alien race who basically seeded all life, Ronan in return led the charge against Thanos and his generals who had taken Earth while the Avengers were away. He was even part of a team for a time assembled by Cosmo, that space dog with the astronaut uniform in the movie.