Most children who are put into water will be swimming in it within an hour. Lessons not required.
Swimming is no more difficult than walking. There is only one catch, don't panic or you die.
When I explained to my children that all they had to do to swim was hold their breath underwater until they could stand up again, they were off like fish. They started in the shallow end and were very soon diving in the deep end.
People are naturally buoyant, if they don't panic, they can swim.