'Inexperienced' in the Bible

David said, “Solomon my son is young and inexperienced, and the house that is to be built for the Lord shall be exceedingly magnificent, famous, and an object of glory and splendor throughout all lands [of the earth]. So now I will make preparations for it.” Therefore, David made ample preparations before his death.

And King David said to all the assembly, “My son Solomon, whom alone God has chosen, is still young and inexperienced and the work is great; for the temple is not for man but for the Lord God.

and worthless (unprincipled, unethical) men gathered around him, useless and wicked men, who proved too strong for Rehoboam the son of Solomon when Rehoboam was young and timid, and could not assert himself against them.

For everyone who lives on milk is [doctrinally inexperienced and] unskilled in the word of righteousness, since he is a spiritual infant.