John McKinly established himself as a prominent figure in Delaware through a combination of military service, medical practice, and political leadership. He began his career as a commissioned lieutenant in the New Castle County militia and later served as a major during the French and Indian War. McKinly transitioned to a successful medical practice, becoming a popular physician in Wilmington. His political career included multiple terms as Chief Burgess of Wilmington and representation in the Assembly of the Delaware or Lower Counties. McKinly's contributions extended to founding the Delaware Medical Society and serving on the Newark Academy Board of Trustees, where he advocated for education funding.

John McKinly exhibits a nuanced ideological positioning, blending moderate views on independence with a commitment to local governance. His strategic philosophy appears highly localized, as seen in his dedication to regional militias and local educational institutions. McKinly's rhetorical style likely emphasizes community and regional identity, creating an intriguing tension between his moderate stances and the radical fervor of the independence movement.