The message of the kingdom has been consistent right from the beginning.

We were created as physical beings with the intention that we would rule over the earth.

Then God said, “Let Us make man in Our image, after Our likeness, to rule over the fish of the sea and the birds of the air, over the livestock, and over all the earth itself and every creature that crawls upon it.”

So God created man in His own image;
     in the image of God He created him;
     male and female He created them.

God blessed them and said to them, “Be fruitful and multiply, and fill the earth and subdue it; rule over the fish of the sea and the birds of the air and every creature that crawls upon the earth.”

Genesis 1:26-28

But then the fall happened.

From there, God selects a man (Abraham) from which He would begin building a nation (Israel).

Now if you will indeed obey My voice and keep My covenant, you will be My treasured possession out of all the nations—for the whole earth is Mine. And unto Me you shall be a kingdom of priests and a holy nation.’

Exodus 19:5-6

And then a long and sordid history of repeated failures. Throughout that ugly history of failure, God uses His prophets to communicate in detail, the restoration process. It would come through one man in the line of David.

For unto us a child is born,
     unto us a son is given,
     and the government will be upon His shoulders.
And He will be called
     Wonderful Counselor, Mighty God,
     Everlasting Father, Prince of Peace.
Of the increase of His government and peace
     there will be no end.
He will reign on the throne of David
     and over his kingdom,
to establish and sustain it
     with justice and righteousness
     from that time and forevermore.

Isaiah 9:6-7

There would be some very real and tangible outcomes as a result of this restoration.

The wolf will live with the lamb,
     and the leopard will lie down with the goat;
the calf and young lion and fatling will be together,
     and a little child will lead them.
The cow will graze with the bear,
     their young will lie down together,
     and the lion will eat straw like the ox.
The infant will play by the cobra’s den,
     and the toddler will reach into the viper’s nest.
They will neither harm nor destroy
     on all My holy mountain,
for the earth will be full of the knowledge of the LORD
     as the sea is full of water.

Isaiah 11:6-9

This restoration is reinforced by many, many statements throughout the New Testament...

Your kingdom come.
     Your will be done,
     On earth as it is in heaven.
I have eagerly desired to eat this Passover with you before My suffering. For I tell you that I will not eat it again until it is fulfilled in the kingdom of God.
For I tell you that I will not drink of the fruit of the vine from now on until the kingdom of God comes.
Then the King will say to those on His right, 'Come, you who are blessed of My Father, inherit the kingdom prepared for you from the foundation of the world'.
Heaven must take Him in until the time comes for the restoration of all things, which God announced long ago through His holy prophets.
You are the ones who have stood by Me in My trials. And I bestow on you a kingdom, just as My Father has bestowed one on Me, so that you may eat and drink at My table in My kingdom, and sit on thrones, judging the twelve tribes of Israel.
You have made them to be a kingdom and priests to serve our God, and they will reign upon the earth

So, when we die, our spirit returns to the Lord (Ecc 12:7) - temporarily. But that's not the end of the matter. Our destiny is not to roam around in heaven as disembodied spirits.

Just as man is appointed to die once, and after that to face judgment, so also Christ was offered once to bear the sins of many; and He will appear a second time, not to bear sin, but to bring salvation to those who eagerly await Him.

Hebrews 9:27-28

By the word of the Lord, we declare to you that we who are alive and remain until the coming of the Lord will by no means precede those who have fallen asleep. For the Lord Himself will descend from heaven with a loud command, with the voice of an archangel, and with the trumpet of God, and the dead in Christ will be the first to rise. After that, we who are alive and remain will be caught up together with them in the clouds to meet the Lord in the air.

1 Thessalonians 4:15-17

The kingdom of heaven and the kingdom of God are synonymous terms.

They're describing the same thing.

Don't confuse the statement "kingdom of heaven" with a "kingdom in heaven".

For the moment, its locale and dominion is in heaven. But it isn't confined to there forever.

“Behold, the dwelling place of God is with man,
     and He will dwell with them.
They will be His people,
     and God Himself will be with them as their God.
‘He will wipe away every tear from their eyes,’
     and there will be no more death
or mourning or crying or pain,
     for the former things have passed away.”

Revelation 21:3-4

Consistency matters!