No, not all primates have opposable thumbs. While many primates, especially those in the family of great apes such as humans, chimpanzees, and gorillas, do possess opposable thumbs that allow them to grasp objects and manipulate their environment effectively, there are several species that do not have fully opposable thumbs.
For example, some monkey species, like the tamarin and marmoset, have a thumb that is not entirely opposable. Instead, their thumbs are more limited in movement, which restricts their ability to grasp objects in the same way. This difference can be attributed to their ecological niche and the types of tasks they need to perform in their habitats. In contrast, the capabilities of having opposable thumbs give species like humans a significant advantage in tool use and complex manipulation.
In summary, while opposable thumbs are a common feature among many primates, they are not universal to all species within the primate order.