It’s a Buff Brahma. Slow maturity is very common in the breed when you have chicks late in the year. Here’s my cockerel when he was young. He took an unreal amount of time to feather in :)
The legs are yellow and it has a pea comb. It’s not even a first generation mix of Marans. Marans are homogeneous for white skin (meaning all offspring would have white skin). Pea combs are dominant so would never just pop up. He’s a mixed breed
This is the only Brahma pullet. The dark and other two lights are cockerels. Your black cockerel chick is really bizarre. Does he have brown?? Can you get some better pictures? He’s a poor example of a breed or just a hatchery-mix like a Whiting True Blue. What assortment? Your final cockerel is...
I’m not seeing clearly willow legs by any means. Some birds just don’t have bright yellow legs at first. My Legbars were vaguely willow at first and developed into more clearly yellow later. Unless they’re clearly green, I wouldn’t say that rules out Leghorn at all. I have poor connection right...