Mr. Steinkauler was found to be a native born citizen because he was born in the mainland USA (St. Louis).
Maybe you need to read the letter rather than Birther sites. In the letter AG Pierrpont says, "The status of young Steinkauler, and his right to protection from the Government of the United States, depends primarily upon his nationality. Nationality is either natural or acquired. The one results from birth, the other from the operation of the laws of kingdom or states...Young Steiukauler is a native-born American citizen. There is no law of the United States under which his father or any other person can deprive him of his birthright. He can return to America at the age of twenty-one, and in due time, if the people elect, he can become President of the United States..."
Attorney General Pierrepont agrees that there are two forms of citizenship, and that natural-born and native born are synonymous. Link
U.S. v. Wong Kim Ark, 169 U.S. 649 (1898) -- The holding in U.S. v. Wong Kim Ark states that Wong Kim Ark is a "native born citizen."
No, the holding was: "The foregoing considerations and authorities irresistibly lead us to these conclusions: the Fourteenth Amendment affirms the ancient and fundamental rule of citizenship by birth within the territory, in the allegiance and under the protection of the country, including all children here born of resident aliens, with the exceptions or qualifications (as old as the rule itself) of children of foreign sovereigns or their ministers, or born on foreign public ships, or of enemies within and during a hostile occupation of part of our territory, and with the single additional exception of children of members of the Indian tribes owing direct allegiance to their several tribes. The Amendment, in clear words and in manifest intent, includes the children born, within the territory of the United States, of all other persons, of whatever race or color, domiciled within the United States. Every citizen or subject of another country, while domiciled here, is within the allegiance and the protection, and consequently subject to the jurisdiction, of the United States."
Ark was found to be a citizen by birth, AKA a natural-born citizen. Nothing in the Ark decision supports the idea that there are three or more classes of citizenship. Nothing in the decision identifies or implies that there is a difference between citizen at birth and natural-born citizen. Link
Now go back under your rock.
Now stick your head back up where it usually resides and keep on looking.