which one do you think
1 a Frenchmen named Monique built the first one
2 a manufacturer built a wrench that when you twist the handle the monkey opened his mouth
bob w.

Looked like a Monkey head & mouth opens when tail (handle) was turned..

picture

I vote no on both options.  Monique is very unlikely to morph into monkey.  There are a lot of monkeys in English (monkeyshines and so forth) slang.   Not sure what made English speakers think of monkeys in making slang.  Seems to be several things that added monkey to make a phrase.  Monkeyshines reflected the seeming foolish activities of the creatures.  Grease monkeys worked up in the rafters to keep the old line-shaft shops lubricated.  Monkey-tail cannons were small ship's cannons (couple of feet long or so) that had a tiller attached to the rear that reminded people of the tails of the critters.

Maybe we should monkey around to find the earliest reference to monkey wrenches.

One story is that a guy named Moniky ( or various other spellings) had some of the adjustable screw wrenches and he had told his co-workers not to "monkey" with his wrenches.
The more likely origin is the resemblance to a monkey face.

This has been discussed many times over the years with no consensus reached.

Aaahhhemm!! I'm right here and I can see what you are saying!