Steve doesn't have much of a personality nor a real goal on his own. He never talks, all he really does is actions related to the player's choice.
Powers and Abilities
Steve is capable of carrying over four hundred thousand tons of materials, running fast, fighting hordes of various monsters, and he never has to sleep. Steve is also capable of building huge creations with no help at all. He can also build portals, use alchemy, and shoot arrows far.
Since the common theorized story of Minecraft is that Steve is trying to save the world and Testificates from the Endermen army and their leader the Dragon, it can be based on that Steve is caring and brave. However; since his personality is based on you, it's up to you to decide what he does and how he acts. Is Steve going to risk everything for the Testificates, is he going to procrastinate and save the world later, is he going to be a morally ambigious anti hero who constantly steals from the Testificates and makes it rather unclear whether he's doing it for the greater good or just his own selfish gain, or is he not even going to be the slightest bit heroic and just run around mindlessly killing animals and testificates not even trying to save the world? Another factor is what mode you pick, if you pick Hardcore mode and fail that ultimately means that Steve failed his quest to save the world and that the Ender-Dragon succeeds in whatever his goal was, however; if you chose survival mode and died you simply come back without your tools.
Steve's default clothes are blue pants and a shirt, though, with editing you can change his clothes and apperance completely.