Sometimes we need to experience falling - in order to learn how to get back up again.
The same goes for children. They need to fall from time to time. When children fall, they learn to get up, wipe themselves off, and continue on. They learn how to persevere: a very important trait we need through life, when the going gets rough.
It is so easy for the mommy instincts to take over, if we see our children climbing on new obstacles and say, "be careful! Don't fall!" I even catch myself doing it at times. However, I'm not convinced we need to give them as many warnings as we are preconditioned to do. Most of the time, the child is already being cautious and carefully assessing the environment on their own, as they navigate the foreign terrain. In fact, giving too many verbal commands can make the child more cautious and fearful with movement--hindering them from fully developing as nature intended.
Hearing, "be careful" from adults is what therapists call an auditory cue. If children get too many auditory cues, this also takes away from their ability to use the essential senses of vision, muscle sense, and balance--all critical when walking and running around new obstacles.
Falling is simply part of a learning process for children. As our body goes to fall, our brain learns to adapt and children learn to put their arms out to protect their head. As they get more practice with falling, they start to anticipate the sensation and shift their body weight to prevent the fall. These adaptive responses help children organize incoming sensations, to create a more mature brain.
If we try to prevent all falls, even the little ones--children may not learn how to adapt their bodies to falling. I once worked with a preschool-aged child that was carefully protected from falling. She never learned how to shift her weight appropriately or how to put her arms out to protect herself. This made her even more unsafe. Therefore, keeping children from falling all the time can actually cause them to be unsafe.
Kids need to challenge themselves and take risks in order to fully develop their bodies and their brains. Our job is to keep them safe; ironically, that means letting them fall from time to time.