Yes Jesus is the mediator between men and God, the Bible does't teach two different classes or groups. The problem is with the witness teaching, They combine two scriptures other sheep and great crowd. Look at these two different scriptures
John10:16 16 I have other sheep, too, that are not in this sheepfold. I must bring them also. They will listen to my voice, and there will be one flock with one shepherd.
Romans 8:9-11 9 But you are not controlled by your sinful nature. You are controlled by the Spirit if you have the Spirit of God living in you. (And remember that those who do not have the Spirit of Christ living in them do not belong to him at all.) 10 And Christ lives within you, so even though your body will die because of sin, the Spirit gives you life [ d ] because you have been made right with God. 11 The Spirit of God, who raised Jesus from the dead, lives in you. And just as God raised Christ Jesus from the dead, he will give life to your mortal bodies by this same Spirit living within you.
Even the NWT says in Romans 9 However, YOU are in harmony, not with the flesh, but with the spirit, if God’s spirit truly dwells in YOU . But if anyone does not have Christ’s spirit, this one does not belong to him.
The way I see it from the scriptures, to be one of Christ sheep-other sheep, to belong to Christ as Romans says they must have God's Spirit IN them not on them, thus making one as the Greek word here for Christ IN you, Translated "ANOINTED"
I don't get the feeling that there are two groups, classes, one might as well be Hindu and believe in Classes or Castes. Christ in the Mediator for men as the Bible says. No self exaulted position of looking down at others.