Heh! Yes and no. They're all outcasts of some sort.
Triton is from the Sea of Fallen Stars, nowhere near the Sword Coast and the North where everything is happening. He's literally a fish out of water. He's on a bit of a personal quest to find the storm giant that lived near his triton village, that one day just upped and disappeared. He was an aloof, grumpy storm giant, but for some reason the triton considers the giant his friend.
Goliath is outcast from his mountain clan because he has a big mouth and insulted the chief's son. Was basically told to "make his own place in the world" in order to avoid bloodshed. He seeks to defeat more and more powerful monsters, and changes his nickname every time he defeats a stronger one. Currently he calls himself "Giantkiller" (but started off as "Ratkiller").
Tabaxi is an orphan from a faraway jungle land that has been visited by Faerunian sea traders for the last several years. Since he was always in the way, nobody was particularly sad to see him go when he was "adopted" by a ship navigator (who was also an artificer, and who taught him everything he knows). Navigator died at the hands of some organized crime syndicate because of unpayable gambling debts. Tabaxi ran away with his master's thunder cannon and went off to seek his fortune.
Yuan-ti is a pureblood who can pass for human. Not evil but not very good, either. Sole survivor of a disastrous diplomatic mission to xenophobic theocratic human settlement when yuan-ti nation of Najara was "declared". Decided not to go back. Interested in exploring other humanoid nations and observing how political and economic systems can thrive (gasp!) without slavery.