It's not that this is wrong -- certainly, if you speak about "un renard" to a French person, they will know you're speaking of a fox -- but it's that it's not entirely true, either. It also omits my favourite part of the tale.
The word for "fox" in French is in fact "goupil".
Back in the Middle Ages (12th-13th century), there began to be written, collected and/or redistributed a set of folk tales involving animals. These animals are anthropomorphised and have names: the cat Tibert, Chanteclerc the rooster, Tiécelin the raven, Ysengrin the wolf, Hermeline the vixen and, most famous of all and the one who gave his name to the collection of these tales, Renart the fox.
Le Roman de Renart is a really fun collection of tales about Renart, trickster extraordinaire.
Renart goes by many variations on his name: Reynhard, Renard, Raynard, Regnard, Reinhart... He tricks the wolf out of hams. He becomes godfather to a bird's children. He's funny, he's charming, he's a rogue -- he's Robin Hood!
But by far the greatest trick Renart ever pulled was convincing the French that there are no foxes but him -- or perhaps, that he is all the foxes and all the foxes are he.