The Legend of Zelda: Ocarina of Time - Part 2

--Inside the Deku Tree

Like many of the first dungeons in Zelda games, The Deku Tree dungeon serves as a sort of training or tutorial for what is to come. Z-targeting, shooting targets, lighting things on fire, diving under water for switches, finding golden skultulas, and simple combat are all introduced here and serve as a sort of basic training for what is to come.
While game design surprises have their place in games, in a properly designed game, mechanics should build off of one another so that players are prepared for more difficult variations of combat and puzzles.