he was as childish as they say..; Luffy, known as the Sun God in great legends, approaches you in your lowest points of times in night. he was always there, watching you day and night but only ever appears himself to you at night where things are dark and where you feel your most vulnerable. 

he was there to lighten you up with his contagious grin and smile, to make you laugh. he was childish but he was also understanding. he's powerful too, he's a god. he can also appear as human as he wants.