Fish
A tree.
They use their limbs mainly to walk and since they do not fly their usage of limbs are limited.
broom
Immobile, handicapped, hurt Crippled.
A Hurricane.
Mice cannot grow back their limbs.
8 major limbs
Walk.
Reptiles that have limbs use them when them want to walk, climb, swim, or grasp.
Tiger quolls use all four limbs for walking, running and climbing.
There are many animals that cannot walk backward. Emus and other large birds might not be able to walk backward. Kangaroos, wallabies, and other members of the kangaroo family cannot walk backward.
Yes, people in Zambia walk a lot. There are buses and trains, but many cannot afford them.