John the Baptist was a very different person from all other men. He was prophesied of and was created to be the Forerunner of Jesus Christ. He was a very special and blessed person unlike all other men that have ever lived. John the Baptist was the Forerunner of Christ. One has to understand the implications of this to understand how he differs from all of us.
As for suffering the little children to come unto Him, Jesus is not saying they are believers as in being Christians/disciples of Him. What He is saying is that they are blameless in His sight for they have not yet reached the age of accountability. Knowing right from wrong, good from evil, and that should they die in this state, they would surely be with Him in heaven for He lays no blame at their feet. This does not mean that they heard the Gospel, realized their sinful nature, repented, confessed their sins and asked Jesus to come into their lives as Lord and Saviour, and became disciples of Christ, ergo, Christians...........Big difference.
The Scriptures I offered show this fairly clearly.........and there are others as well.
They are not "born again" for Jesus Himself says that being "born again" is as becoming like a new baby.............innocent and trusting......When we are first saved/born again, our spirits are born anew in Christ and we become babes in Christ. That is why a new believer is fed with milk........until they grow in understanding and are able to feast on the meat of His Gospel. Just as children are first fed on milk until they mature and are able to feast on meat.
One is not born a Christian. Jesus never says they are, nor did any of the Disciples. God's salvation plan for mankind is laid out in detail throughout the Bible.
God bless
(edited to say)
We must remember if it were possible for us to be born Christians/disciples of Christ, then that makes His sacrifice on the cross of no avail. There would have been no need for Him to have come down in the form of man, suffer all He did, be crucified, buried and resurrected.