Here's a little background information on some of the Secret of Mana characters.
In Secret of Mana, the playable characters have no set names, but for common knowledge, the hero is the boy. You start out as the boy who is an orphan that lives with the town elder. While playing with two of the local children in a forbidden area of Potos, the boy falls off from a log bridge into a pool of water. As he wanders around he finds a sword in the center of another pool of water and he hears a voice telling him to take the sword. As he does a bright light flashes and for a few seconds the boy sees a ghost (who turns out to be the boy's father). With this sword, the boy has unknowingly started on his destined road to be the Mana Hero. Try using the Sword or Spear for the boy.
You meet up with this smart mouth sprite in Gaia's Naval. Lost when young, the sprite wants to get back to his home in the Upper Land. He decides to go with you, reluctantly at first, until you get him home. The Sprite will turn out to be your main source for attack magic and I found is very good with the axe or boomerang.
The girl is actually the princess of Pandora. Her father wants her to marry against her will and the main reasons she goes with you is to escape her father as well as find her love who was kidnapped. She is bossy but she is your source for defensive magic. She can even cast spells onto your weapons, giving you the power of a certain elemental. I found she uses the whip or the Spear the best.