KINGDOM HEARTS

I am reading KIGNDOM HEARTS by SHIRO AMANO I think that the key in SORA's hand unlocks any door I think that becausethe end is shaped like a crown.But before I read I have a question why does he have that key.He has the key so he can find the heart of every world.As I was reading I came across the word evidentlyand didn't knowwhat it ment so I asked my dad found out it means you like something/someone more than the other