Creeping Jenny has another, perhaps more common, name of Moneywort. The name Moneywort comes from the leaves, which are the size and shape of coins. The use of “wort” as a suffix in plant names comes from the Old English word, “wyrt”, which just means plant. Therefore Moneywort means “Money Plant”.
As far as the name “Creeping Jenny”, there is some speculation that it refers to the fact that it was once used as an herbal remedy for “chinne” cough (whooping cough). The name would have originally been “Creeping Chinne”, but morphed into “Creeping Jenny” when people no longer knew what “chinne” was.