"In the beginning God created the heaven and the earth." God and heaven are two different words throughout Scripture and do no have the same meaning. The kingdom of heaven was prophesied and preached to the Jews only concerning the coming of their Messiah and King who would re-establish Israel's kingdom and sit upon the throne of David forever. The arrival of this prophesied one was good news to Israel as the King and His kingdom was at hand during Jesus' earthly ministry.
Jesus was also pointing to another kingdom in existence, the kingdom of God. This kingdom is the dwelling place of the born again believer. It was kept in mystery form until after the resurrection or it would not have led to His crucifixion. 1 Cor. 3:7-8.
The nation of Israel rejected their King in both aspects, so the Lord would turn to the Gentile world with the preaching of the kingdom of God, the spiritual aspect of the kingdom. The kingdom of heaven was not for the Gentile or Samaritan. See
Matthew 10
5 These twelve Jesus sent forth, and commanded them, saying, Go not into the way of the Gentiles, and into any city of the Samaritans enter ye not:6 But go rather to the lost sheep of the house of Israel.
7 And as ye go, preach, saying, The kingdom of heaven is at hand.
Even after the resurrection, the disciples were looking forward to this earthly restoration of the kingdom:
Acts 1
6 When they therefore were come together, they asked of him, saying, Lord, wilt thou at this time restore again the kingdom to Israel?
7 And he said unto them, It is not for you to know the times or the seasons, which the Father hath put in his own power.
8 But ye shall receive power, after that the Holy Ghost is come upon you: and ye shall be witnesses unto me both in Jerusalem, and in all Judea, and in Samaria, and unto the uttermost part of the earth.
They were now commissioned to go to the Gentile world and Samaritans with the preaching of the cross, not the kingdom of heaven which is only meant for the nation of Israel. This preaching will come back into play when the Father says it's time.