Thank you for this question. I remember when I was new to Revelation, and even upon hearing it taught that it was Mary and Jesus, thought it quite odd. One has to wonder why John, a contemporary of Mary, and someone who would have immediately recognized her, failed to identify Mary by name? There is no question in my mind if John had seen Mary, he would have identified her. The same goes for the man child. Why would John not immediately identify this person as Jesus? He certainly would have recognized him as he was with him on Earth, saw him glorified at the Transfiguration, and met with him after Jesus' resurrection. The truth is this was a sign/wonder representing a summary of the past, as well as the future events at mid-tribulation.
John takes you back to the beginning of time and shows you the spiritual battle of the devil against God's chosen people who would produce the Word, Jesus. Note that the dragon "stands" continually seeking to devour - Joseph, the male children of Israel born in Egypt, Haman's plot in Esther, while Jesus was alive (Bethlehem, the temptation, the many attempts on his life), the fall of Jerusalem and dispersion of the Jews among the nations, the pogroms, persecution, the holocaust, and the coming tribulation.
Mary is NEVER described in scripture in such terms, but there is a description in the Old Testament that sounds familiar to Revelation 12:7 - Jacob/Israel's family.
Genesis 37:9 (KJV)
9 And he (Joseph) dreamed yet another dream, and told it his brethren, and said, Behold, I have dreamed a dream more; and, behold, the sun and the moon and the eleven stars made obeisance to me.
And in another place, a pretty interesting parallel verse to what we see in Revelation 12.
Isaiah 66:7-8 (KJV) 7 Before she travailed, she brought forth; before her pain came, she was delivered of a man child. 8 Who hath heard such a thing? who hath seen such things? Shall the earth be made to bring forth in one day? or shall a nation be born at once? for as soon as Zion travailed, she brought forth her children.
Catholics will never understand Revelation because they have been taught that the "church" has superseded the nation of Israel which is a total corruption of scripture.
I think that error has filtered into a few denominations. The Christian college I attended my freshman year was teaching some interesting things concerning Revelation. The moment you start trying to force the Church into Revelation, you end up in the proverbial religious ditch. And you rob Israel of their proper place in prophecy.
Here is where catholics trip themselves up:
Nothing in scripture is about Mary, anywhere.
Even when Mary is mentioned, it is all about her son, not her.
Mostly when she is mentioned, it is not by name, but by her relationship to her son: “Thy mother...” or “there was a marriage in Cana of Galilee; and the mother of Jesus was there”
The Bible is not about the mother, it is about the Son!