Jesus didn’t mention any such office of “Royal steward”. That is fanciful embellishment, and no pope claimed such a title for hundreds of years.
If Peter had the office he would have operated in that official capacity instead of an apostle equal to the others, and his sole successors for hundreds of years after.
So here is Peter addressing the many in different areas (writing a Papal letter and acting of a Steward-servant) as leader of the Royal Priesthood, a Holy Nation .
Salutation
1 Peter, an apostle of Jesus Christ,
To the exiles of the Dispersion in Pontus, Galatia, Cappado′cia, Asia, and Bithyn′ia,[a] 2 chosen and destined by God the Father and sanctified by the Spirit for obedience to Jesus Christ and for sprinkling with his blood:
May grace and peace be multiplied to you.
And the Letter states they are all one nation.
The Living Stone and a Chosen People
1 Peter 2 So put away all malice and all guile and insincerity and envy and all slander. 2 Like newborn babes, long for the pure spiritual milk, that by it you may grow up to salvation; 3 for you have tasted the kindness of the Lord.
4 Come to him, to that living stone, rejected by men but in God’s sight chosen and precious; 5 and like living stones be yourselves built into
a spiritual house, to be a holy priesthood, to offer spiritual sacrifices acceptable to God through Jesus Christ. 6 For it stands in scripture:
“Behold, I am laying in Zion a stone, a cornerstone chosen and precious,
and he who believes in him will not be put to shame.”
7 To you therefore who believe, he is precious, but for those who do not believe,
“The very stone which the builders rejected
has become the head of the corner,”
8 and
“A stone that will make men stumble,
a rock that will make them fall”;
for they stumble because they disobey the word, as they were destined to do.
9 But you are a chosen race,** a royal priesthood,**
a holy nation, God’s own people,[a] that you may declare the wonderful deeds of him who called you out of darkness into his marvelous light. 10 Once you were no people but now you are God’s people; once you had not received mercy but now you have received mercy.
This is all very scriptural to have One Universal Church with a Papal leader and St. Peter was the first.
Mark 3: 23 And he called them to him, and said to them in parables, “How can Satan cast out Satan? 24 If a kingdom is divided against itself, that kingdom cannot stand.