Childish (adjective)
Of or suitable for a child.
Childish (adjective)
Behaving immaturely.
“Your childish temper tantrums are not going to change my decision on this matter.”
Childlike (adjective)
Innocent and trustful; credulous; artless.
Childlike (adjective)
Of, like, or suitable for a child.
“childish|childly”
Wiktionary