Nice job on the fish, and you got down correctly all the key areas of occlusion for the monkey. When it comes to separating occlusion and form shadows, most of the darkness you see when an object is under direct light will be the form shadow, but there is a gradation as the occlusion fades out or a strengthening as it interacts with other planes, including the floor. Think of a soft, diffused light source coming from above. So in this monkey example, you will see some soft general shadows, underneath the face/cheek area and a soft shadow underneath the brow bone, similar to the gradation on the sides of the fish. Generally, the shadows will become darker the closer they are to the floor (or another plane, as in the case of tight crevices) and lighter the further away and more open they are.

I improved on the drawing because my lines were too heavy in the previous submission. I tried to focus more on the ambient occlusion itself

No idea if it’s entirely correct and the soles of feet I assumed would be in contact with the ground.

In ambient occlusion the question to ask your self is what fraction of the light in the hemisphere above a surface's normal can see light (and remembering that the flux of incoming light drops off with the cosine of the angle---so light from grazing directions is not as important). With AO we often imagine the entire sky is lit with ambient light, but that's a simplification. I think your fish may be a bit too shadowed. All in all, great progress!

Good job! This ambient occlusion work makes well feel the volumes.

Good work!! You are definitely getting the hang of this. Here are a few suggestions on the mug. The other two look solid!