All of my kid's toys are animals of some kind. Birds, giraffes, ducks, donkeys (no elephants, of course).
We visited some friends yesterday who just welcomed their third - a boy - who joined his two older sisters and two energetic but friendly boxers (ooooh, the Fidg was IN LOVE with those dogs. When she wasn't backing away or running to mom for cover).
We congregated in the living room/playroom where there were mountains of interesting new toys to check out. So what did she go for?
She zeroed in on a [human] baby doll. Walked right over and plucked that thing right up. Carried it around. Mostly she just chewed on its head.
I don't know what this all means. But I don't think it means baby girls have an instinctual need to mother toys, objects or people.
Before we left, she was on to a kid's digital camera. I liked seeing that.