The presence of the kid was the main thing that moved this up to 3 stars in my mind. Having him solve the riddles the adults couldn't figure out was implausible, but it made the movie relatable to children.
That made me realize: This is a kids movie.
If you're a kid who's never seen the movies this one liberally borrows from (Indiana Jones and the Last Crusade, The Goonies, The Mummy), then Fountain of Youth is decent enough.
For an adult, the movie isn't bad - you've just seen it before. And it was better the first several times.
