Simba is the protagonist of the 1994 film 'The Lion King'. As a young cub, Simba ends up losing his father in a wildebeest stampede and is blamed for it by his evil uncle Scar. Simba ends up running as far as possible from his home, The Pride Lands, and ends up encountering Timon and Pumbaa. Timon and Pumbaa teach Simba about the lifestyle of Hakuna Matata and help him to grow into a stronger lion.
However, it isn't until the arrival of Nala and Rafiki, which the latter summons the spirit of Mufasa, that Simba realizes that he cannot shirk his responsibilities and heads back home. He confronts Scar, whom admits to killing Mufasa, and after a fight, Simba defeats Scar and claims his throne as the King of the Pride Lands.
After which, he claims Nala as his queen, and becomes the father of Kion and Kiara. [And also Kopa in 'The Lion King: Six New Adventures']
Role in the Sorcerers of the Magic Kingdom. Edit
While he isn't directly shown nor mentioned in the game, the fact that Scar is dead and has been resurrected by Hades indicates that this takes place after the events of the first film and possibly happens during or even after the time of 'The Lion Guard' and 'The Lion King II: Simba's Pride'.