These seem to be clearly stated:
*** w91 2/15 p. 18 par. 11 "You Were Bought With a Price" ***Nevertheless, in a preliminary way, the great crowd have already "washed their robes and made them white in the blood of the Lamb." (Revelation 7:14) Christ does not act as Mediator of the new covenant toward them, yet they benefit from this covenant through the work of God’s Kingdom. Christ still acts toward them, however, as High Priest, through whom Jehovah can and does apply the ransom to the extent of their now being declared righteous as God’s friends. (Compare James 2:23.) During the Millennium, they will gradually "be set free from enslavement to corruption [until finally they] have the glorious freedom of the children of God."—Romans 8:21.
*** w89 8/15 p. 31 Questions From Readers ***The people of all nations who have the hope of everlasting life on earth benefit even now from Jesus’ services. Though he is not their legal Mediator, for they are not in the new covenant, he is their means of approaching Jehovah. Christ said: "I am the way and the truth and the life. No one comes to the Father except through me." (John 14:6) All who will gain life on earth must direct their prayers to Jehovah through Jesus. (John 14:13, 23, 24) Jesus also serves as a compassionate High Priest who is able to apply in their behalf the benefits of his sacrifice, allowing them to gain forgiveness and eventual salvation.—Acts 4:12; Hebrews 4:15.
Consequently, 1 Timothy 2:5, 6 is not using "mediator" in the broad sense common in many languages. It is not saying that Jesus is a mediator between God and all mankind. Rather, it refers to Christ as legal Mediator (or, "attorney") of the new covenant, this being the restricted way in which the Bible uses the term. Jesus is also a corresponding ransom for all in that covenant, both Jews and Gentiles, who will receive immortal life in heaven. The apostle John referred to these at 1 John 2:2. But he indicated that others too will receive the benefit of Christ’s sacrifice: "He is a propitiatory sacrifice for our sins, yet not for ours only but also for the whole world’s."
***Worldwide Security
chap. 1 pp. 10-11 par. 16 The Desire for Peace and Security Worldwide ***
Was Moses the mediator between Jehovah God and mankind in general? No, he was the mediator between the God of Abraham, Isaac, and Jacob and the nation of their fleshly descendants. Likewise, the Greater Moses, Jesus Christ, is not the Mediator between Jehovah God and all mankind. He is the Mediator between his heavenly Father, Jehovah God, and the nation of spiritual Israel, which is limited to only 144,000 members. This spiritual nation is like a little flock of Jehovah’s sheeplike ones.—Romans 9:6; Revelation 7:4.