Salvation was always by grace thru faith heir.
Noah "found grace" in the eyes of the Lord. (Genesis 6:8 KJV).
God told Noah to DO something; to build an ark. Noah prepared an ark at the saving of his house.
Hebrews 11:7 KJV By faith Noah, being warned of God of things not seen as yet, moved with fear, prepared an ark to the saving of his house; by the which he condemned the world, and became heir of the righteousness which is by faith.
You and I were never asked to DO anything.
Cornelius was already saved before he heard the gospel,
That's one of the craziest things I have ever heard anyone say. I guess all of Peter's preaching was all for not. If he was "already saved", Peter wouldn't have preached he that feareth God and worketh righteousness is accepted with Him. If he was "already saved", Peter would have never told him to believe on His name for the remission of sins. There would have been no need to believe for the remission of sins.
he was a believer and had accepted the content of faith required BC for salvation.
Cornelius' prayers and alms had come up for a memorial before God Acts 10:4 KJV~the promise to Abraham~ Genesis 12:1-3 KJV). He was up for a blessing.
The content of faith required for salvation changed thru history beginning in the garden onto Noah's and Abe's and Moses, and Yeshua's but salvation was always by grace thru faith and never by works.
While it's true that all salvation, Genesis through Revelation, requires faith; not all salvation in the Bible is/will be by grace through faith (Ephesians 2:8-9 KJV). James wrote 2:18 KJV, James 2:20 KJV and James 2:24 KJV
Many (future) wait to go through the trial of their faith: receiveing the end of their faith, even the salvation of their souls. Of which salvation the prophets enquired and searched diligently, who prophesied of the grace that should come unto them (notice too, that it is of the grace that should come unto them).
1 Peter 1:7 That the trial of your faith, being much more precious than of gold that perisheth, though it be tried with fire, might be found unto praise and honour and glory at the appearing of Jesus Christ:
1 Peter 1:8 Whom having not seen, ye love; in whom, though now ye see him not, yet believing, ye rejoice with joy unspeakable and full of glory:
1 Peter 1:9 Receiving the end of your faith, even the salvation of your souls.
1 Peter 1:10 Of which salvation the prophets have enquired and searched diligently, who prophesied of the grace that should come unto you:
That is NOT the same as trusting the Lord's faith and finished work in our place believing 1 Corinthians 15:1-4 KJV. It's a done deal! We didn't DO anything! Ephesians 2:4-9 KJV
Peter went to Cornelius with the gospel.
I've shown over and over in this thread the gospel that Peter preached to Cornelius.
Paul checked his gospel with Peter and James in Acts 15 to get their approval, to see if they preached the same gospel, they did and affirmed his gospel by not adding to it.
Peter, James and John didn't know “that gospel” that Paul preached among the Gentiles until he "went up by revelation, and communicated" it unto them . It was THEN (not before) that they saw that the gospel of the uncircumcision was committed unto Paul. It was THEN (not before) that they “perceived the grace” that was given unto Paul!
Galatians 2:1-2 KJV Then fourteen years after I went up again to Jerusalem with Barnabas, and took Titus with me also. 2 And I went up by revelation, and communicated unto them that gospel which I preach among the Gentiles, but privately to them which were of reputation, lest by any means I should run, or had run, in vain.
Galatians 2:6 KJV But of these who seemed to be somewhat, (whatsoever they were, it maketh no matter to me: God accepteth no man's person

for they who seemed to be somewhat in conference added nothing to me:
They added nothing to Paul?! If they had been preaching the same gospel as religious men would have us to believe all of those years surely THEY must have added something to Paul. According to the scriptures they DIDN'T!
BUT CONTRARIWISE,…!
Galatians 2:7-9 KJVBut contrariwise, when they saw that the gospel of the uncircumcision was committed unto me, as the gospel of the circumcision was unto Peter; 8 (For he that wrought effectually in Peter to the apostleship of the circumcision, the same was mighty in me toward the Gentiles

9 And when James, Cephas, and John, who seemed to be pillars, perceived the grace that was given unto me, they gave to me and Barnabas the right hands of fellowship; that we should go unto the heathen, and they unto the circumcision.
If mad is teaching Paul had the gospel before Peter did, it is an error.
The Body of Christ began with the apostle Paul (then Saul), not Peter!
Concerning the gospel: The King James Bible is the final authority. And it says:
Galatians 1:11-KJV But I certify you, brethren, that the gospel which was preached of me is not after man. 12 For I neither received it of man, neither was I taught it, but by the revelation of Jesus Christ.
Paul could not call it "my gospel" (Romans 2:16 KJV, Romans 16:25 KJV, 2 Timothy 2:8 KJV) if it was committed unto someone else. The dispensation of the gospel was committed unto Paul (1 Corinthians 9:17 KJV) not Peter, James or John! It was a mystery before revealed to and through Paul (Romans 16:25-27 KJV, 1 Corinthians 2:6-7 KJV).
Study to shew thyself approved unto God, a workman that needeth not to be ashamed, rightly dividing the word of truth!