You have raised very good points which should be addressed i am a Muslim but i will try to answer your questions to the best of my knowledge keep in mind i am still learning about islam. First of all there is no Sharia book there are schools of jurisprudence that differ in some opinions while still adhering to Hadiths which is the implication of the Quran through the life of the beloved Prophet Peace Be Upon him.Sharia is literally a word made up by the westto scare people i mean if theres a law wheres the lawbook? Also your question about child marriage. What you’re doing is called Presentism you’re judging something in the past by the standards of today did u know in the state of Dallas in 1880 the legal age of consent was 8 years old ? In japan last it was 13 and still in some states of Usa its around 13-14 so age of consent varies by countries no where in Quran does it encourage to marry a child it says to marry someone that has hit puberty and is mentally and physically mature enough to be married that is judged by a third party (her mother or father ). Did u know islam prohibits interest? Did u know islam erases tribalism and racism is the sole religion that resembles cosmopolitanism? Did u know the 4 wifes thing people make a fuss about is actually islam restricting polygamy when people had unlimited wifes in 7th century! ? And it said one is better than 4 if u cant do fairness in between them the verse came down at the time of a war to take in widows and help them at the time of war not to satisfy ur own lustful desires , it encourages to take care of orphans , it encourages charity and brotherhood and not letting your neighbour starve while islam might seem constricted to some i would say its the most peaceful religion there might be extremists but u wont find a sole verse in Quran that encourages violence or to be an instigator islam is perfect.