This looks like a French copper marans plus something else. Is it a marans/junglefowl cross? It is the roo I have, along with 2 hens for the chocolate colored eggs, plus others for "bird watching", a blue/red laced wyandotte, speckled sussex, prairie bluebell egger, & a couple of buff orpington for friendliness and egg production.
I doubt it has any maran in it. What it was originally hybridized with would depend on its source of origin and whether its of hatchery stock or not. The farm I got them from wouldn’t or couldn’t tell me. Leghorn is one possibility if it originates from Cackle. Old English game bantam is another, and is more of what I suspect. I can’t tell the hybrid eggs from old English game bantam eggs and when I had a OEGB flock I had to take care to keep the eggs separate when collecting.
Originally the first gen looked a lot more like miniature American games and I’ve been selecting them to conform more to the wild phenotype. I have another line I’m conforming to American game bantam show standards. I have threads on each project.