what is the highest ranking given to a person in the afore-mentioned armed forces?
A five-star rank.
United States Armed Forces
These are ranks of the highest honor and responsibility in the U.S. Armed Forces, but they are almost never given during peacetime and only a very small number of officers during wartime have held a five-star rank:

No corresponding rank exists for the Marine Corps, Space Force, or the Coast Guard. As with three- and four-star ranks, Congress is the approving authority for a five-star rank confirmation.
who was president of the us in 1985 Ronald Wilson Reagan . where was he born? Tampico, Illinois. did he have a career in movies prior to entering politics? Yes, he signed a deal with the Warner Bros. studios. what has he acted in? "Love Is on the Air", "Dark Victory", "Santa Fe Trail", and "Knute Rockne, All American". which state was he the governor of? California. who was president of the country before him? Jimmy Carter. what is the other title given to a person holding this office? The commander -in-chief. what are they the commander of? Of the United States Armed Forces. what does this role entail? It gives the ultimate responsibility for the direction and disposition of the military.
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United States Armed Forces [SEP] Five-star ranking
It has been held by two people: John J. Pershing who received the rank in 1919 after World War I and George Washington who received it posthumously in 1976 as part of the American Bicentennial celebrations. Pershing, appointed to General of the Armies in active duty status for life, was still alive at the time of the first five-star appointments during World War II and was thereby acknowledged as superior in grade by seniority to any World War II–era Generals of the Army. George Washington's appointment by to General of the Armies of the United States was established by law as having "rank and precedence over all other grades of the Army, past or present", making him not only superior to Pershing, but superior to any grade in the Army in perpetuity.