Your first question, who thought of the system, has a straight answer. From Wikipedia:
> Hanyu Pinyin was designed by a group of mostly Chinese linguists, including Wang Li, Lu Zhiwei, Li Jinxi, Luo Changpei, as well as Zhou Youguang (1906–2017), an economist by trade, as part of a Chinese government project in the 1950s.
By the way, they are not “English” characters; they are Latin/Roman characters, and used in a huge number of languages with different spelling conventions. Pinyin was created for the entire world to use, not specifically English speakers.
> Hanyu Pinyin was designed by a group of mostly Chinese linguists, including Wang Li, Lu Zhiwei, Li Jinxi, Luo Changpei, as well as Zhou Youguang (1906–2017), an economist by trade, as part of a Chinese government project in the 1950s.
By the way, they are not “English” characters; they are Latin/Roman characters, and used in a huge number of languages with different spelling conventions. Pinyin was created for the entire world to use, not specifically English speakers.