I do too. To be clear, I did NOT mean that we could go without it today. What I meant was that if we didn't have it to start with, things would've likely still developed albeit much more slowly.
I'll also preface this by saying I definitely slightly misread everything before and so my reply was kinda crappy
5 meters is definitely way too short for the chair swing ride. Look at the people in the seats. It's definitely at least 10 meters.
Assuming 10 meters and 100 km/h, that gives about 7.9 g. That's in the range of what fighter pilots might experience and well beyond where most people black out, so that's still definitely too high.
Looking it up online, this is a pretty classic physics problem and the numbers you might see around it are closer to a radius of 12 meters and a speed of 13 to 17 m/s. Taking that as 15 m/s (54 km/h), that works out to about 1.9 g, which I can subjectively say feels much closer to the real value if you ever ride on one of these.
So, the second one is about 1.9 g