Well, Gannaed, you knowledge of American History is lacking. You picked a couple of statements by a few men who although they were major participants in the Revolutionary period do not express the opinions of all our founding fathers, especially those who arrived on the Mayflower.
As to the 10 Commandments more than 3 were laws of this land. Sunday closing laws, adultery, perjury (lying), stealing, and murder either are now illegal or were illegal until fairly recently in our history. 3 of the 10 commandments have to do with worshipping God, the other 2 -- coveting (the basis for most murders, thefts, and lies), and honoring parents, are parts of the moral code of religions other than Christianity. So the 10 Commandments are not all that unique to Christianity. Every state in the United States refers to God in their constitutions.
As to the 10 Commandments getting center stage in a courthouse? I personally don't believe they belong in a secular building that routinely grants no fault divorces in violation of Biblical teachings on divorce, and promotes one religion over another in violation of the First Amendment to the Constitution, however, I would not have a problem with the monument being placed at the entrance of the court house as a historical reminder of the reason this country was founded, freedom to practice Christianity as one chooses. Moses and the 10 Commandments are on the Supreme Court building, the top of the Washington monument is capped with praise to God, and there are many other examples found in our Capitol. At least 3 branches of my family came to America for religious freedom, one on the Mayflower, one 13 years later and one in the early 1700's to escape persecution of the Mennonites in Switzerland. So Christians founded this nation, regardless of what you want to believe.