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.
Next time you can try lying flat on your back in even less water depth, let’s say around the belly? Try keeping afloat by focusing on your breathing (you can look up inverted breathing), and when you feel like you’re dipping too much, your legs can always correct course by contacting with the floor. It depends on your morphology, but arms extended up and hands above your head works well for me (the position babies sleep in). Then tilt your head backwards a little, chest puffed, let your back arch naturally. That’s my method, you can try it
I had done that a lot. I don’t see any luck in that sense, even compared to other things.