If you’re looking for an adjective for a baby, don’t use “angelic.” The baby you are looking at is the furthest thing from it. A search through Tanach, and for this I’m relying on my daughter, Ethel – a Chidon Tanach finalist, who charges too much for research assignments – shows this to be true. Angels in Tanach are generally unpleasant. They are often terrifying or demonstrating their message with a sign. Some hold swords, and several come with accusatory words. And as such, the feeling they inspire is likely not amazement but awe, often with some confusion. If we look at the Talmud, the salient feature about angels isn’t child-like characteristics. If someone resembles an angel in the Talmud, it’s because they earned your absolute respect as your master has, is fasting, or is wrapped in white. And I assume the baby in question cannot cover wide distances in just a few hops. Later, there are all sorts of medieval debates, within various faiths, about what angels are capable of. None of that pertains to babies. In the medieval glosses on the Talmud, we get a glimpse into the abilities of angels. Their facility for almost all languages – and the ability to read inner thoughts – makes the comparison to infants particularly odd.
Perhaps you’re thinking of cherubs. Those may be described as having a childlike face, based on the Talmud. But cherubs are also characterized in Tanach as weapon-wielding guardians, and several medieval Jewish thinkers see them as referring to intelligence, so that reference doesn’t fit either. We use the word angelic probably due to medieval art, and not of the Jewish variety. So, if you do use the word, what you really mean to say is, “that baby looks like a Caravaggio or a Botticelli.” That is certainly a compliment, but not a particularly Jewish one.