Characterizations of Apocalypse have varied through the years. In his initial appearances, Apocalypse was depicted as a mutant supremacist, but he slowly became more of a character with concerns of the evolution of mankind and how it must progress; he tests mankind to provide his own form of natural selection, culling the weak from the strong in order for humanity to grow stronger.
shitty character outside the animated series
He's honestly written to be a lot more awesome than he probably was in actual comics. He sounds like he could be an awesome deus ex machina villain but i doubt he was ever used well.
thats exactly what they are using him for in Messiah War.