"Diaper" isn't named after a person - it is a very old English word for material with a pattern of diapers on it i.e. diamond shapes. When, what we call nappies were first made, they were, I think, diamond shaped, so they were called originally diapers.
The name stayed in the US, but in Britain, they eventually became called nappies, short for napkins.
The word "faucet" has a similar history - many British people think of it as a strange American name for a tap, but it is actually an old English word that was gradually replaced by "tap".