But learning from experience is the worst possible way to learn something. Learning from experience is one up from remembering. That's not great. The best way to learn something is when someone else figures it out and tells you: "Don't go in that swamp. There are alligators in there."
Works great for avoiding alligators. Fails miserably for riding bikes.
Hiking destinations. I have a longtime friend and hiking buddy who really likes tough, exposed hikes up to the top of something, with a perverse derision towards anything resembling a freshwater source anywhere along the hike. But he also can't stand mosquitoes. At all. So, he might say, "Don't go in that meadow, there are mosquitoes in there." For me, they're annoying, but I like little hidden meadows, so maybe I want to go there.
And, also, there's a chance that you'll figure out something that nobody else has. You go in that swamp, even though someone warned you about the alligators, and you manage to avoid the alligators but you get a cut while you're in there and you discover that the swamp muck does something interesting with cuts, it actually disinfects them and helps them heal better.
My dad used to say that a smart man learns from his mistakes and a wise man learns from others'. The older I get, the more skeptical I become about that.
Learning from your own mistakes instead of others' is a high-variance strategy. Our culture is better off because of the people that do it, but if you're selfishly looking to maximize your own expected value, you'll put great weight on the majoritarian view.
If someone sets up the seat for you and explains how to shift and brake and rides with you a little bit, I'm sure learning would go much faster than if you were just left in a driveway with a bike and told to figure it out.
As for how I learned to ride, my dad took me to a hill, sat me on the bike and pushed me down. I learned how to ride pretty quick...well until I hit a small stump hidden by the grass.
After that I was mostly fine and learned to ride pretty quick.
If you want a kid to learn to ride a bike, remove the fear of failure. Do it on a gently sloping grassy hill that levels out, for example.
When I first learned to ice skate I learned that falling on ice fucking hurts. I didn't learn to ice skate. I learned to not fall over. Then my friend dressed me up in his team's goalie's pads - I pretty much bounced back up again if I fell over. By the end of an hour I could do the sprint exercises with the team and keep up (over short distances anyway!).