I find something curious about Mr & Mrs Manoah. Judges 13 picks their story by informing us that the woman was barren. Well, it was a test of their love that despite that challenge they were still together. But like similar cases in the Bible that problem was only meant to be temporary. And as in all biblical examples, too, the product from such marriage would be a champion for God. Meanwhile an Angel was sent to communicate the mind of God to the family. One would expect that such message should come first hand to Manoah, being the husband and head of the union. That was not to be as the Angel went straight to the woman to give her the good news, which she eventually relayed to her husband. The man, now growing inquisitive, prayed that God might send the messenger back. God obliged him; but again the Angel appeared to the woman while she was in the field. Is this a case of Manoah not knowing how to be in the right place at the right time? For unless we know the mystery of accurate and timely positioning we will never be able to hear, see, and do what God has in mind. Well, this could only be a matter of speculation.
God works with people who are open and accessible. When God finds such people the issue of gender is set aside. God does this to prove that He is not a respecter of persons. Anyone who meets His conditions is accepted by Him.
The other way to look at this is to understand the way God works. Usually He looks for an entry point into a family or an organization to carry out His will. This entry point is anyone who is attuned to spiritual vibe. God works with people who are open and accessible. When God finds such people the issue of gender is set aside. Age does not even count when God is looking for access. We have known of families where it is one or two of the children that understands and yearns for God. They simply become the priests of their families as God honors them and confirms their word. God does this to prove that He is not a respecter of persons. Anyone who meets His conditions is accepted by Him.