We will rule and reign with Him which was God's original plan but man gave the deed to the ranch away...In Genesis 1 God gives humankind "dominion" over all the things on the earth. It was intended we would rule this realm under His Lordship. The rules were very simple...live, eat, love, make babies, subdue, replenish, prune...there was not much we were not to do and all we had to do was knowing His love and concern be aware that His warnings from love were serious...He was God and knew/knows the end from the beginning...but we fell for the gospel of doubt, questioning God's word and His motives and saw in our vanity a power in deciding good and evil for ourselves (Genesis 3:5)...we listened instead to Belial and now suffer the consequences of spiritual separation from our loving father (Isa. 59)..so because God gave this dominion to man and man lost it to the present ruler of this world, it would take a man to gain it back, but we could not because all will eventually sin and thus we are in bondage to this death...so He became a man (sent His Son) to free us from this curse.
Hebrews 2:14Forasmuch then as the children are partakers of flesh and blood, he also himself likewise took part of the same; that through death he might destroy him that had the power of death, that is, the devil; 15 And deliver ( to snatch away, rescue, save) them who through fear of death were all their lifetime subject to bondage.
So though as yet sinners, Christ died for us...so the Son of God came as a son of man so the sons of man could once again become the sons of God...