Kinetic power is lower, that said you can still hurt yourself pretty bad depending on how you fall. A wrist doesn't need a lot of force to break, nor a skull needs to fall from high to cause trauma. A cyclist on a sidewalk going at 20km/h can cripple a child for life (not that the cyclist cares, but just for the example).

I broke my wrist by falling from my bike when I was younger, almost while stopped (my wheel got blocked in a tram rail).

And yet if you look at the public health statistics for the things _actually_ crippling children for life, "other people on bikes" are a very long way down the list - at least in most places; I don't know if Paris has a specific problem there. You can hurt yourself pretty bad in the home, after all - the major causes here seem to be cars and dogs.

(Before we even consider that - at population level and in developed Western countries - lack of physical activity, and an environment which actively suppresses it through sheer indifference if not outright hostility - is likely inflicting a far greater burden on childrens' health and wellbeing than trauma).