"Les hommes mangent des éléphants."
Well it's not about the sentence itself. It's just to see how the words you are learning fit into a context. A rather bizarre context in this case, but let's not focus too much on the real world practicality of these things.
Whilst you are correct that the words fit, I really think that sentences such as 'men are boys' and 'men eat elephants' and so on are utterly pointless. Would it not be better if we just focussed on real life sentences that we are likely to hear or use ourselves?
When they put ridiculous sentences like this in it makes you question yourself as to whether you are translating it correctly.
I got that wrong because I thought that was too weird to be the answer.
Some of our ancestors used to hunt mammoths. Besides, the point of these is to strike a balance of retaining what we learned previously and learning something new. For that to work out, sometimes you'll end up with funny sentences.