https://www.jwfacts.com/watchtower/mediator.php
If Jesus is only mediator for the few thousand remaining remnant on earth, who is mediator for the millions of Jehovah's Witnesses that do not form part of the 144,000?
"The "great crowd" of "other sheep" that is forming today is not in that new covenant. However, by their associating with the "little flock" of those yet in that covenant they come under benefits that flow from that new covenant." Watchtower 1979 Apr 1 p.31
"They recognize that they are not spiritual Israelites in the new covenant mediated by Jesus Christ, nor part of the "chosen race, a royal priesthood, a holy nation."-1 Pet. 2:9. Yet they do benefit from the operation of the new covenant. They benefit from this just as, in ancient Israel, the "alien resident" benefited from residing in among the Israelites who were in the Law covenant.-Ex. 20:10; Lev. 19:10, 33, 34; Rev. 7:9-15. To keep in relationship with "our Savior, God," the "great crowd" needs to remain united with the remnant of spiritual Israelites." Watchtower 1979 Nov 15 p.27 Benefiting from "One Mediator Between God and Men"