I think it’d be good to start with the papacy as set out in the Bible.
You could mention how Christ changed Simon’s name to Peter, which means “rock” and how Christ said that on this rock, he would build his Church and that the gates of hell would not prevail against it.
Further, he asked Peter 3 TIMES, and Peter alone, to shepherd his sheep. Peter was listed first of the apostles and the clear leader, in the absence of Christ. Christ told Peter that later, he’d need to strengthen his bretheren. Peter alone is given the “keys to the kingdom”.
Christ said that all authority in heaven and earth had been given to him. In turn, he gave authority…besides the keys, Christ told Peter, alone, that what he held bound on earth would be bound in heaven. What he loosed on earth would be loosed in heaven.
Now, we believe Peter held what we would now call an “office”. Notice that when Judas committed suicide, the apostles replaced him with someone else, I think it was Matthew.
In this same way, Peter, when martyred, also was replaced, so that the Church would never be without leadership.
This is an apologetics cheat sheet. Scroll down to “papacy”.
ewtn.com/library/ANSWERS/WALLET.HTM
Now, one thing the Catholic Church has is the pope.
Another thing we have is the Magisterium. You could show how the apostles were given special abilities, NOT given to others. They were given the power to forgive sin, for example. Christ breathed on them and told them to receive the gift of the Holy Spirit, that sins they forgave would be forgiven. Again, their offices were replaced, and they made some rules and Church laws, I believe under DIVINE authority.
Some will not acknowledge Catholics as Christians, but we are actually the original “Christians”, there from the beginning.
Later, other churches split off…like when Henry VIII couldn’t get an annulment and went out and headed his own church.
Christ said he was establishing his “Church”, NOT “churches”! We believe there’s only one true one, the original.
As to not offending anyone. If you are writing this paper to a group of mixed faiths, someone would probably take offense, though. People would disagree. You’d need to realize this, upfront. However, you could be gentle, polite, and back your beliefs with quotes, etc., to make it more persuasive.
Look into the topic “apologetics” (defense of the faith) for further information.
Good luck!
