Unity confuses you? Why?
Unity is an operational principle for the universal church. How does that then define the RCC as the True Church?
But there is a deeper issue: Protestants are not going to unite with those they believe are theologically in error. It is the right understanding of God, Christ, and the Scriptures, which teach us, not unity for unity sake.
If you will forgive the analogy, the Democrats call bipartisanship agreement with their line of thinking. Bipartisanship is when the two sides have an open discussion, and work out an agreement. There is much in Roman Catholic theology that is unacceptable to Protestants...and there will be no "unity" if those differences can't be work out. And claiming to be the only True Church will not help those discussions.