APPARENTLY, you do not know how to read a SCOTUS opinion ...
It begins with a question, continues with DICTA, and ends with the decision. The only two parts that are relevant are the question and the decision. The dicta is an explanation of the reasoning AND NOT the decision.
DICTA: Opinions of a judge which do not embody the resolution or determination of the specific case before the court. Expressions in court's opinion which go beyond the facts before the court and therefore are individual views of author of opinion and NOT binding in subsequent cases as legal precedent. State ex rel. Foster v. Naftalin 246 Minn. 181, 74 N.W.2d 249.
The Ark case could, should, and was decided SOLELY on the basis of the 14th Amendment. Justice Horace Gray wrote the opinion, so the dicta reflects HIS opinion. Gray was appointed by Chester Arthur who, himself, had questions about his eligibility to hold the office of President.
The dicta concerning English Common Law he included in the opinion was ENTIRELY irrelevant to the disposition of the case. The case hinged upon birth within the United States, as per the 14th Amendment, and the phrase "and subject to the jurisdiction thereof". Since Ark [and his parents] spent most of their lives in the United States [until his parents returned to China in their old age] and the fact that Ark remained a resident of the United States, the jurisdictional issue was settled.
So, why did Gray include the references to English Common Law? Who knows - perhaps he was a friend of Arthur and wanted to help him out by trying to squash the questions of his eligibility [reputation-wise]. BTW, Gray bastardized and even flat-out lied concerning the meanings some of the citations in his dicta.
But more importantly, why DIDN'T Gray declare Ark to be a "natural born citizen" instead of just declaring him to be a "citizen"? He CLEARLY thought that Ark was natural-born.
The reason is that the other justices that formed the majority in Ark WERE able to declare him a "citizen" under the 14th Amendment, but WERE NOT willing to declare him "natural-born". So, for Gray, half a loaf was better than none ...
FINALLY, if Ark DID settle the "natural-born citizen" question, WHY hasn't it been cited as precedent under the stare decisis doctrine [the doctrine of precedence]? The reason is that Ark DID NOT decide the issue.
Now, if you want to debate the point(s) with me concerning English Common Law, you better do A LOT of reading first [I have]. You CANNOT trust the dicta in the Ark opinion, so I suggest that you read Calvin's Case, Dicey, the De Natis Ultra Mare Act [1351], Cowell's legal definition [1701], the Act of Settlement, the Laws of William I, and the British Nationality Act of 1730, to name a few.
If ‘dicta’ was irrelevant, they wouldn’t write it. It isn’t binding, but it explains their reasoning and is often used to guide future questions - as has the dicta of WKA.