I've been riding for many many years. And when it comes to falling/crashing, things happen so fast that there really is no reaction time.

And each fall is different. Sometimes putting your hand out with gel'd glove will protect you. Sometimes putting your hand out will break your wrist or forearm or damage your elbow.

Sometimes trying to roll to keep from breaking your hand or arm, you could break your collarbone.

This is why you should wear a pair of gloves and a helmet! Gloves preferably gel'd ones. Instinctively most people will put their hands out to break the fall.
That little gel padding in your glove does give you some added protection.