As the play opens he has just proved himself a superior soldier in battle. He is already a lord, but his performance on the battle field wins him the new title of Thane of Cawdor.
One of the oddities of the play is that he is married to a woman (now Lady Macbeth) who has had children, but Macbeth has no children. The Scottish Lord upon whom Macbeth is based was married to a woman who was older than he. Presumably the Macbeth of the play must have gained some additional wealth and/or advantage through the marriage to a woman who enjoyed some position. Since the King was invited to stay at Macbeth’s castle we can assume he had the advantage of some wealth and prestige.
