Before she married, my daughter bought a cute black puppy. This dog turned out to be the size of a small horse. A great big Great Dane, the largest I have seen personally.
That dog lived with her and protected her, later her and her husband, and later from their first girl all the the way through their third daughter.
He lived with them, the babies grew up with him, and he with them, I guess. Long story short, extremely tolerant, forgiving and loving dog to the girls and family, and fiercely (I mean very fiercely protective of the family in total, of the girls in particular). The dog never once bared his teeth to any of them.
I have been around really good, nice large dogs that are indeed part of the family and never bared their teeth to any family member, we have owned many. I still stand by my belief that babies and toddlers and large dogs should be separated unless there is hands on adult supervision. The size difference means if that dog does get aggressive with that child- even once the results can be horrific.
Maybe part of my belief is from the fact that we always had horses and big dogs and my mother was very aware of the fact that horses and large dogs can do major damage to a small child. Interactions with horses and large dogs was treated the same by my mother- it just didn’t happen without an adult directly supervising every moment of the encounter. Our horses and dogs were really nice too, but the size difference meant if anything happened accident or other reaction of the animal the result was not going to be good.