Snollygoster
determining the bloodline in the goblin bank? this has always puzzled me. gringotts bank. not a hospital. and besides the fact that magic related to blood is considered forbidden, the goblins themselves are forbidden to use magic after the uprising. they are ordinary bank custodians. and not jack-of-all-trades. the story is some kind of children's story. absolutely not logical.
I sincerely hope he isn't the heir to anything substantial it would make the starting point note you put in the description disingenuous as he wouldn't be a muggleborn and he wouldn't be starting with nothing, it also sets a precident for the mc getting things he doesn't earn i.e. large sums of money, artifacts, spell tomes etc. Borrowing money from harry is fine since you've said he'll pay him back, as long as he doesn't borrow a ton of money and invest it in some company he has prior knowledge of to get super rich since that would also be something he didn't earn, It doesn't feel like your gonna go down that route but I'll reserve judgment until later