Moreover, if God "knit us together in our mother's womb," how can He then say certain ones aren't able to serve in the priesthood because of the way He made them? Aren't we ALL fearfully and wonderfully made?
The priest's role was not only to make atonement for the sins of the people, but to typify both the sacrifice and the coming Christ - both of which were to be without spot or blemish. The reason God required that the priests were to be physically whole and "perfect" was because they represented Christ to the people. They were establishing a picture in the hearts and minds of Israel of the coming Messiah. "Such a high priest truly meets our need—one who is holy, blameless, pure, set apart from sinners, exalted above the heavens." Hebrews 7:26
God was drawing a distinction that the Israelites could see visually of what must be true spiritually, that their High Priest must be pure and set apart. He must be different from them, yet one of them.
This distinction of allowing some to serve and others not is often confused in our mind with the value God places on someone or their worth. In the same way, we often think of the restrictions of certain ministry positions to men as a statement of worth. That is NOT what God says here, or in limiting certain roles to men. "Now in a great house there are not only vessels of gold and silver but also of wood and clay, some for honorable use, some for dishonorable. Therefore, if anyone cleanses himself from what is dishonorable, he will be a vessel for honorable use, set apart as holy, useful to the master of the house, ready for every good work." 2 Timothy 2:21
God establishes His purposes for us. We are set apart for that purpose, whether it is one of great attention and impact or one who serves behind the scenes with little notice. Each role is critical and valued by God.