I was thinking about that when I was dropping my 6 year old off at some hobbies earlier - it’s pretty much expected to have learned how to ride a bicycle before starting school, and it massively expands the area you can go to by yourself. When she went to school by bicycle she can easily make a detour via a shop to spend some pocket money before coming home, while by foot that’d be rather time consuming.
Quite a lot of friends from outside of Europe either can’t ride a bicycle, or were learning it as adult after moving here, though.
edit: the high number of replies mentioning “swimming” made me realize that I had that filed as a basic skill pretty much everybody has - probably due to swimming lessons being a mandatory part of school education here.
I was never able to learn Italian as much as I tried and my cousins in Italy were never really able to learn English, then they discovered Friends and after a few years now we’re actually able to communicate. First 20 years of our lives were seeing each other for a few weeks at a time once or twice a year and just doing things beside each other, then we were able to use our phones to translate text messages, but during their last visit we were actually able to talk with each other and it was so nice.