The first climbing ropes were ordinary manila- heavy, not very strong, easily frayed, and very static. The last one of those characteristics was probably the most dangerous. Even a short fall onto a static, stretch-free rope can be painful or fatal. While we still use static rope (technically it's semi-static) for rappelling, modern dynamic ropes are almost bungee-like in their stretchiness. As long as the anchors hold and there are no ledges or inconvenient trees in the way climbers can safely fall for almost unbelievably long distances these days.