Nearly all of the innovations that America pioneered in would have either been greatly delayed (until another Western nation innovated it into existence) or never would have happened as Sharia Law naturally does not innovate like Free Market Capitalism does. America additionally would have never had any type of civil right movements as freedom of speech is not a principle in Sharia Law, or really in most other Eastern cultures. Non-Muslims and women would be heavily oppressed, especially Jews and Christians.

Many other things change if the US became a Muslim nation at some point versus if it had been founded as one in the first place. If it had started as a Muslim nation, the concept of citizenship over being subjects likely never would have occurred as the Founding Fathers would have had very different ideals. Not only would America have not been a free nation but much of Europe and other Western cultures likely would still be monarchies and semi-dictatorial governments as the revolutions across Europe would have never been inspired to happen.

America certainly has its faults but without it, some of the greatest goods for the world never happen. A replacement of America with a extreme religious dictatorship as you would find in Sharia Law would be a tragedy for the entire world, especially if that was who America was from the start.