Mark 4:11 And He said to them, “To you it has been given to know the [d]mystery of the kingdom of God; but to those who are outside, all things come in parables,
Matt 4:17 From that time Jesus began to preach and to say, “Repent, for the kingdom of heaven [c]is at hand.”
The parable of the sower as seen in these two verses are talking to those sowing the seed on earth at the time of Jesus and afterward. Mark uses kingdom of heaven and Matthew the kingdom of God. Why try to made two kingdoms? Jesus is the King of Kings, Rev 19:16 New American Standard Bible And on His robe and on His thigh He has a name written, "KING OF KINGS, AND LORD OF LORDS." Isa 44:6 "Thus says the LORD, the King of Israel and his Redeemer, the LORD of hosts: 'I am the first and I am the last, And there is no God besides Me. Notice thus says the Lord, the King of Israel and His Redeemer, the Lord of hosts, I am the first and the last and there is no God besides Me. The plural both the King of Israel and His Redeemer, which in the opening of the verse, Thus says the Lord and after His Redeemer, the Lord of Hosts. Both are referred to in scripture as the first and the last and then it declares, and besides Me(Who is that Me) there is no God.
Thus says the Lord, worship the Lord thy God and only Him will you serve. There is one True God, manifested in a Triune God head.