The average or common person; also "†man John", "†man Jonathan". Chiefly in "every man jack"noun (also †every Jack man) every single person. "any man jack"noun any person at all.
Origin
Early 19th century.
Definition of man jack in US English:
man jack
noun
The average or common person; also "†man John", "†man Jonathan". Chiefly in "every man jack"noun (also †every Jack man) every single person. "any man jack"noun any person at all.