The laws in #leviticus 15 concerning a woman's monthly cycle seem archaic to people today, but that's because we have become so far removed from the spiritual forces underlying life, blood, and life's cycles. These laws aren't just ceremonial. There are real, spiritual implications to uncleanness.
On the other hand, uncleanness isn't necessarily something to be feared. There are degrees and kinds of uncleanness, and the only ones you really need to be concerned about are those that stem from a disdain for God's commandments. If you become unclean because you simply don't care what God says about it, then the real source of your uncleanness is in your heart, not a physical object or another person.