Today my daughter is 6 months old, a week ago we tried mashed applesau…

Today my daughter is 6 months old, a week ago we tried mashed applesauce after which she had diarrhea with mucus, does this mean that the child is not yet ready for complementary feeding? The apple was liked by her, gave her 2 days of puree Gerber, there were no rashes. There is an interest in food, she takes mugs and spoons from me when we eat. And if I'm being honest, I got confused, it turns out that if the child doesn't sit down, shouldn't you start complementary feeding? But the child can also sit at 7 and 8 months, and if the interest in food disappears by this time? And still, how is it better to start with self-feeding and