Mt 5:19 Whosoever therefore shall break one of these least commandments, and shall teach men so, he shall be called the least in the kingdom of heaven: but whosoever shall do and teach them, the same shall be called great in the kingdom of heaven.
Mt 11:11 Verily I say unto you, Among them that are born of women there hath not risen a greater than John the Baptist: notwithstanding he that is least in the kingdom of heaven is greater than he.
by WAESHAEL: The revealed truth in Mt 11:11 is that John the Baptist was not in the Kingdom of Heaven while alive and in prison. On the other hand some people had entered the kingdom of heaven, even those who were just beginning to understand were allowed in.
by WAESHAEL: God chooses who will enter the Kingdom of Heaven -
those He declares righteous, He converts and makes as
little children. That is, He gives the grace of repentance,
to man, who then is drawn to change his fleshly life,
demonstrates this desire to others, accepts Christ as his
Lord and King, and studies the word of God - as if a
child, accepting all he is taught. And thereby man
enters the Kingdom of Heaven.
by WAESHAEL: So you see here that to enter the KOH requires one to accept Christ as Lord and King. John the Baptist did not do this. He sent his own disciples to ask Jesus whether he was the one they waited for i.e JB did not know Jesus was Christ. And JB died before he could enter the kingdom of heaven. But He was declared by God to be righteous (Jesus calls him "the greatest.") and presumably obtained Life Eternal through the Abrahamic covenant.
“And Jesus went about all Galilee, teaching in their synagogues, and preaching the gospel of the kingdom, and healing all manner of sickness and all manner of disease among the people.” Matthew 4:23, KJV.
Summary: To enter into the Kingdom of Heaven is to enter into a life as taught to the disciples by The Master. A life of doing things for others - healing all manner of sickness - whether physical or spiritual. If you did God's will and showed others "teach others to observe whatsoever I have shown you." Jesus had told the disciples at a later time, then you are the greatest. If, on the other hand you disagreed with God's will, and taught others to disagree, you would be the lowest in the KOH - but you were not excluded from it, because you had accepted Christ as your Lord and King. You were only a "child," and could repent.