Mc isn't a dragon, he's just an exception to the rule. And if I remember correctly, his ability to stop the rampage with non-dragon magic is one of the reasons his magic got sealed by that crappy mage counsel + he became a social pariah amongst mages....
My personal theory that he's some sort of Angel or Celestial race. (Just based on how everyone comments on his rare golden hair, and his golden eyes. Those traits usually get associated with angelic characters. Also, it would make sense for that race to be very secretive/hide their existence, since they're usually even more OP than dragons in fiction.)
I don't think MC is any special race, it's just that from his time there were more mages and ergo more spells, then he got reincarnated where the mages are weak and there's different species that can use magic but still not like his
I swear I read in one chapter that only a dragon could stop a rampaging dragon, so is MC a dragon?? I tot he was a human until then, but that Sus doc was asking about his species… and his taxi driver I assume is a dragon, which also means dragons can hide their horns? So he could have been hiding his horn? But they said a new being that is even stronger than dragons so is he not?? A dragon???