The identity of the servant is an enigma, I believe that the text is ambiguous for a purpose; it allows the actions and the mission of servant(s) to be the focal point, rather than on the identity of the servant. The role of the servant(s), as we will see, is filled with paradoxes and problems, and naming the servant simply adds to the confusion.
To add to the confusion here are translations of the LXX, The Isaiah Scroll, and the NRSV:
Jacob is my servant, I will aid him: Israel is my chosen, my soul has received him; I have given him my spirit; he shall bring forth judgment to the nations….He will shine like fire, and will not be broken, until he has set up judgment upon the earth: and upon his name the Gentiles will hope… and I have given you as a covenant to descendents, as a light to the Gentiles.
Behold my servant, whom I uphold; my chosen, in whom my soul delights; I put my spirit upon him: and his judgment will go out to the Gentiles…. He shall not falter nor be discouraged, until he puts judgment in the earth: and the islands shall inherit his Torah…and I will give you for a covenant of the people, for a light of the Gentiles;
Here is my servant, whom I uphold, my chosen, in whom my soul delights; I have put my spirit upon him; he will bring forth justice to the nations….He will not grow faint or be crushed until he has established justice in the earth; and the coastlands wait for his teaching…I have given you as a covenant to the people, a light to the nations,
While the servant(s) certainly seems to be an individual, in the NRSV and in Qumran, the text of the LXX still insists that the servant is Jacob and Israel.