Complex sentence: However, his position is jeopardized by the arrival of Buzz Lightyear, an astronaut action figure given as a birthday present to Andy, who is convinced that he is an actual space ranger.
Split into simpler sentences: However, his position is jeopardized by the arrival of Buzz Lightyear, an astronaut action figure that Andy get as a birthday present. Buzz is convinced that he is an actual space ranger.