I remember these details: MC was the world’s first hunter but he’s a B-rank or a C-rank so people look down on him now MC is friends with an older hunter who’s an S-Rank and that’s the male lead I’m 80% sure the MC regressed I think the novel was a harem novel
Sounds similar to either There is No Such Thing as a Bad Hunter or The Regressor’s Personality Training, though neither one exactly. You could be mixing up the details of more than one novel