Would you agree that Christ offered himself (full of grace and truth) to the Jews before their fall? That it was their rejection of Him (i.e. salvation) that caused their fall?
The idea of repentance is for the Jews and can be viewed from the parable of the tenants, told in all 3 synoptic gospels. (Matthew 21:33–46; Mark 12:1-12; Luke 20:9-19)
When Jesus and the 12 were preaching from Matt-John, they need to repent of rejecting God their Father in the OT, and believe in his Son is their promised King and Messiah, as foretold by their prophets. The Jewish nation had rejected and killed many of those prophets.
God had mercy on them and now decided to send his Son to them now. But as Jesus told them in the parable of the tenants, they were wicked and decided to slay the son instead, thinking they can then take control of the vineyard. The words they told Pilate was really horrific from this perspective
Matthew 27:25 Then answered all the people, and said, His blood be on us, and on our children.
When Jesus was on the cross, he asked his father to forgive them for this act, because they know not what they do, the Father agreed to Jesus request.
Israel stumbled at the Cross, but were forgiven (Luke 23:34).
They were given another opportunity, after they stumbled at the cross (Luke 13:6-9).
Salvation was still to Israel first before Gentiles, after Jesus rose again (Acts 1:6, Acts 3:26).
That is what Paul was trying to say when he remarked that they did not stumble so as to fall (Romans 11:11).
So when Peter urged his Jewish brothers at Pentecost to repent (Acts 2:38), they are to repent from their horrific act of murdering the Son of God, and accept him once again as the Son of God and their King, since Jesus's resurrection showed, as Peter stated, he is indeed the Messiah and the Son of God. (Acts 2:36)
But Israel finally fell when they stoned Stephen in Acts 7, it was that fall that salvation was now given to the gentiles (Romans 11:11) God blinded the nation temporary, setting his secret plan in motion to save us Gentiles, independent of Israel.