Q. "If most of the Jehovah's Witnesses today are not a part of the 144,000, then what exactly are they?"
A. While the scriptures show that a limited number of 144,000 have the God given hope of living FOREVER as Kings & Priests RULING in God's Heavenly Kingdom with Christ himself, the overwhelming vast majority of Jehovah's Witnesses have the awesome God given hope of living FOREVER on the Biblically foretold paradisaic New Earth as royal subjects of God's Heavenly Kingdom wherein the Scriptures state that such ones will indeed find their exquisite delight in the abundance of peace. (Psalm 37:11, 29; Isaiah 65:17, 20-23; Matthew 5:5; 2 Peter 3:13; Rev 21:3-5).
While the vast majority of the Churches of Christendom teach that there is but only one final destination for the faithful of God's chosen people, the Holy Scriptures teach and show that there is in fact not one but TWO final destinations for the faithful of God's chosen people (Ruling in Heaven or The foretold Paradisaic New Earth). Almighty Jehovah God by means of His Holy Spirit through Christ determines who goes where in accordance to His divine will and everlasting purpose.
~ NOTE: I am a dedicated and baptized member of the unified worldwide Christian Congregation of JEHOVAH'S Witnesses.