(Warning: the following is a short, somewhat simplistic, overview… and I’m focused on Orthodox and Conservative, not Reform Judaism)
Remember that Judaism, as a religion, is primarily a law code: the Pentateuch contains laws, behavioral (“Thou shalt not steal”) and societal (law courts and penalties) and ritual (laws of sacrifice) and intrinisic (“Thou shalt not covet.”) When the Israelites had their own country (roughly 1200 BC - 70 AD), these were the laws of the land, upheld by the courts and enforced by the authorities.
After the destruction of the Jewish nation by the Romans, rabbinic authorities needed to find a way to adapt the laws to thenew situation: individuals, families, and small communities that did not have self-governance. So, they discussed and debated and disputed how best to adapt the religion. They were, however, discussing what they saw as a law code. Yes, they got involved with incredible minutia, but if you look over the law codes of the US, you’ll find the same minutia. Laws set forth things like “Rest on the seventh day” or “Stop at red lights.” Legal opinion decides what is meant by “rest” or “stop.”
The rabbis decided that “rest” means to “refrain from work” – it doesn’t mean to just relax and enjoy yourself. And “work” was defined as the 39 (IIRC) forms of work that were done in building the Temple. Wikipedia lists them Shabbat - Wikipedia
The rabbis then have intrepreted these over over the centuries. Is turning on an electric light the same as kindling a fire? Is roasting food the same as baking? Is driving a car similar to plowing? And so forth.
Sexual relations are not forbidden on the Sabbath; to the contrary, they are encouraged. So “becoming pregnant” is fine.
The wiping after defecation is (as already noted) not itself a problem, but tearing toilet paper is. Thus, the orthodox or very devout will pre-tear toilet paper or use flushable wipes, etc.
To an outsider, these may seem like petty and unimportant considerations. To Orthodox and Conservative Jews, these are rules that help define life, that add order and organization to chaos, and that bring holiness to the world. And, I should add, all rules of sabbath observance fall away if life or health are endangered.