Ben, the Holy Spirit overshadowed Mary ONCE. You are telling me that the Church did not know that ONE occurence resulted in Mary being with Child? That Jesus Christ was conceived with that ONE act? Can we have some common sense here?
*sigh*
The greek does not use the word conception, as I just showed.
Yes, the Church knew - after the fact. But at the time of her pregnancy, no. It would not have been known, nor anything would have been known about her pregnancy or how she got pregnant.
I know this is hard to wrap your head around, but you have to try taking yourself back to then - not now.