JMNT(i)
1 Now within that hour the disciples approached Jesus, [as a group] saying, "Who, consequently, exists being greater (= most important) within the heavens' reign (or: the kingdom of the atmospheres)?"
2 Then, after calling a little child to Himself, He placed (set; stood) it [Greek is neuter: = a boy or a girl] within their midst,
3 and said, "Truly (or: Depend on it; Amen) I am now saying to you men, If you folks are not turned around [from going in this direction, or reverse your present trend of thinking] and may birth yourselves (or: become) like little children, you can (or: may; would) by no means enter into the heavens' reign (or: the kingdom of the atmospheres; or: heaven’s sovereignty).
4 "Therefore, whoever will be progressively bringing himself low in attitude, situation and condition, so as to be humble, insignificant and unimportant in his own eyes, like this young child – this person is the greatest (= most important) with the heaven's reign (or: the kingdom emanating from the atmospheres).
5 "And whoever would take in his arms and welcomingly receive one such little child – on [the basis and premises involved in] My Name (signifies: character, authority; identity) – proceeds to take Me in his arms and continues welcomingly receiving Me.