Who is the first known boxer, or memorable boxing pioneer that comes to mind: - from Ancient history or - from Early London prize ring rules or - from Marquess of Queensberry rules or - from UK or - from USA ? Maybe, you like to share some ideas, thoughts, or anecdotes...
Luis Ortiz was known to have competed in the Roman arenas despite being past prime he made a good account of himself in the hand to hand events that would later go on to become boxing.
Luis Ortiz jokes will never get old. Boxing fans have only been telling them since the time of Figg and Broughton, after all.
Epeius and Euryalus had a mythical boxing match in the Illiad, all we know about Euryalus is he won a title eliminator against a certain "King Kong", likely the first reference to Luis Ortiz.
From what I know the earlist depictions of boxing are all artwork (which goes back to the bronze age), but we don't know the names of any of them. The first ancient olympic boxing champion was Onomastos of Smyrna who you can read about here.