According to the law, Obama’s mother was a US citizen despite Obama being born in Kenya. Thus, he was eligible to run for president.......Everything else is just a distraction.
Per USC law at the time covering such circumstances of a child born of a U.S. citizen mother and a foreign national father, Stanley Ann was not old enough to pass on her U.S. Citizenship to her son. She would have had to have been age 19 to do that. And she was not yet 19. If Obama was not born in the USA, then he has no claim to U.S. Citizenship whatsoever.
At the time Obama was born, the law required a woman married to a non-citizen to have lived in the US for ten years, five of those after the age of 14, in order to transmit US citizenship to her child. Obama’s mother was still 18.
Actually, there are significant differences of opinion about what a natural born citizen is, and if he was not born in Hawaii, and had only one parent who was a citizen, it's not clear that he is/was eligible.