Man and boy

Hello.
I've run into an interesting expression reading a book. It's 'Man and boy'. I looked it up and as I understand it means 'From childhood', but I still use it hesitantly. Can you read several sentences of mine and tell me if they're correct? I'm struggling with its position in the sentence, and also: Can I use it only with singlural male noun/pronoun or I can use it even for plural male nouns/pronouns?

1) He, man and boy, dreamed of joining the army and protecting his homeland.

2) Adam, man and boy, worked at that convenience store.

3) His sons, man and boy, showed deep disinterest in his father's business.

I really appreciate your help!