The truth is that all the intermediates between humans and their ancestors (which diverged from the common ancestor of humans and chimpanzees) are now extinct (and there was likely no fundamental distinction between humans and their ancestors).
Rim brakes. Rim brakes are so called because braking force is applied by friction pads to the rim of the rotating wheel, thus slowing it and the bicycle. Brake pads can be made of leather, rubber or cork and are often mounted in metal shoes. Rim brakes are typically actuated by a lever mounted on the handlebar.
A grinding noise on braking is usually caused by a lack of brake pad material; the pads and rotors are now metal to metal, with no braking material left. Brake pads are like bars of soap. Eventually they get used up, and you have to replace them and spend a little money.