I would suggest a young lad with an ability to carve and an imaginative libido. One not yet experienced in the true body proportions that only experience can give. IMHO ;-)
Life was hard then ~ far more than we can imagine. That someone invested the time necessary to carve this piece suggests it served far higher purposes than pornography.
This is the very moment of delivery.
The more I look at this the more I realize it is a set of instructions for everyone involved in the birth of the baby.
This is the correct position for everything. (Having read Beck's Obstetrics a time or two "way back when" we had pregnant ladies in the office and my own kids were on the way).