Humans have a lot of homologous structures in common with other animals, and several of these structures are no longer in working order in human bodies. These nonfunctioning structures are called vestigial structures. They still show evidence of common ancestry, but they do not do the same things in humans as they do in other animals.
Some examples of vestigial structures in humans include the appendix, which is a remnant of a larger cecum that was used for digesting plant material in our evolutionary ancestors. The coccyx, or tailbone, is another example of a vestigial structure that was once used for balance and in movement, but is no longer functional in humans.
Other examples of vestigial structures in humans include wisdom teeth, which were necessary for our ancestors' diet of harder foods but are now often removed due to crowding and lack of space in the human jaw. The muscles that control our ear movement are also considered vestigial, as they are remnants of muscles that allowed our ancestors to move their ears independently to better detect sounds.
Overall, vestigial structures in humans provide evidence for evolution and the common ancestry of all living organisms. They are examples of how our bodies have evolved over time, adapting to new environments and lifestyles while retaining remnants of our evolutionary past.