According to quantum mechanics, particles such as the ones you are made of can indeed exist in a wave-like state until they are measured or interact with their environment, at which point their wave function collapses to a specific position. This behavior is known as wave-particle duality.
Now, when we talk about particles and their wave-like behavior, it's important to note that this behavior becomes significant on the scale of atoms and subatomic particles, rather than macroscopic objects like humans. The wave-like nature of particles is not directly observable at larger scales.
While you are ultimately composed of particles that exhibit wave-particle duality, the collective behavior of these particles gives rise to macroscopic objects, like yourself, that appear to have definite positions in everyday life. This is because the wave-like behavior of individual particles becomes less significant as the number of particles increases.
The process of wave function collapse occurs when a particle interacts with its surroundings, causing it to localize to a specific position. In everyday life, the interactions between particles that make up your body and the surrounding environment are so numerous and complex that the overall wave function collapses to a specific position, giving the appearance of a definite location.
In summary, while the particles that constitute your body can exhibit wave-like behavior at the quantum level, the macroscopic nature of your body and the multitude of interactions with the environment result in a definite position being observed on a larger scale.