Being able to swim and be safe in water is one of the most important lessons a child can learn. Those that can swim are far less likely to do silly things like jumping into rivers, which could be treachorous.
Many years back, when my eldest was born, I heard of toddler swimming lessons (with mum) from my SiL in USA. I enquired at local pool, but they did not do anything back then. A few months on I was contacted as they had started such lessons, and my son went from 14 months old
Some children do take longer than others to get going, but with lots of water play in that first couple of years with Mum/Dad or g.parents, and proper lessons all should be getting their badges well before they start school
My g.children have all gone for water play with their mums from a few weeks old, and I have wonderful photos of them as tiny babies happily under water, eyes wide open, babies are not scared of being submerged. All of them have learned to swim properly by the age of 4 or 5 years old and,not only is this making water play safe for them, but gives so many opportunities for fun