Monkeys acting as humans in art are referred to as "Singerie" which is a French term. This humanization of monkeys is popular.
Here is a link for you about "Singerie":
In order for me to properly assess what you have I will need to know the size and see images of the front, back (do not remove from frame) and a clear, in-focus close-up of the signature.
Please send the photos at your convenience. There is not an extra charge to provide more pictures here.
I will opt-out and your question will open again to all the experts. If someone knows the answer they will post a response to you here. You do not need to re-list your question and this does not cost you extra.
I do hope you find the information that you seek.