(Note to Readers: Young Earth Creationists may find this content to be inconsistent with their beliefs. Please either read with an open mind or find content elsewhere; it is not my intent to offend any of my brothers and sisters in Christ. Thank you.)
So, which came first? This sloth:
Or this one?
Sloths came into the picture far before humans and their sins did. Their common ancestor lived 35-40 million years ago, while ours only arrived on the scene six million years ago. They might be slothful, but it turns out they have the advantage when it comes to evolutionary longevity.
And, after all of that, it turns out the poor animal was named after the sin. 'Sloth' the word has been around since the late 12th century, but sloths were only named such in the 1610's.
If you want to read more about sloth and sloths, check out the Online Etymology Dictionary, which offers useful insights into most words in our language.