but I was wondering if it's genuine
Nothing extraordinary, looks genuine. These white ones are OEM drives.
Also, I read on the web that is more noisy that the average hard drive, so I was expecting to hear a noisy motor, but actually the motor itself is very quiet, I think quieter than the other drives I own, but the drive it's very noisy when it read or write data (it looks like there is a hamster wheel inside). Is it normal?
Motors are mostly silent, yes. It is normal.
Also, not on this unit, but on the other one that I'm testing right now, I noticed a small dent on the enclosure.
If the dent was caused by pressure that's fine. If the dent was caused by an impact it's not fine.
as far it works properly I should be fine?
if you crack your head but then you work properly, it's fine-ish, I guess?