There is this genre in Light Novels, Mangas, Manhwas + Anime that I personally find very fascinating: Human Child being adopted & raised by a Non-Human Protagonist(s) I believe it was the classic novel The Jungle Book (1894) that popurlaized it. But I think it was the Greek Myth of Romulus and Remus being nurtured by a she-wolf that was probably the first kind of story. Correct me, if I am wrong about that! List of my current favourite Examples: Romulus and Remus Mogli - The Jungle Book Space Family Carlvinson Kurogane Communication The Boy & The Beast Princess Mononoke A 5000-year-old Herbivore Dragon Was Recognized as an Evil Dragon For No Reason Somali & the Forest Spirit The Human-Hating Demon Lord Has No Mercy For Little Girls Parenting Diary of the Strongest Dragon Who Suddenly Became a Dad ~Cute Daughter, Heartwarming and Growing up to Be the Strongest in the Human World~ Pearl & Weiss Tamago no Torikago - The Eggs Birdcage (Beautiful Art but the ending...) The Girl from the Other Side: Siúil, a Rún (Plot Twist) So You're Raising a Warrior Uchi no Maou ga Tenshi de tsurai - My Demon Lord Is Such an Angel It Hurts (Special mention: Little Demon Lord Princess being raised by Human Hero) Ishi ni Usubeni, Tetsu ni Hoshi - A Pink Heart Inside Stone, and a Shining Star Inside Steel (Special mention: Little Medusa adopted by a Human Knight Warrior) Blind Girl Isekai Brother Ogre and Slave-chan The Skull Dragon's Precious Daughter The Skeleton Becomes a Cat Dad What do you think about this niche sub genre?
The 'feral child' is a recurring motif in myths, a Jungian archetype not any different from, say, the search for the missing father, the paradise-hell dichotomy, etc.
I only know baby Zeus raised and drink milk from wild goat or wolf or something What about Tarzan? Only those 2 are on my mind right now
Apart from the founding of Rome, the legend of Atalanta. I think there are certain local stories in my culture too reflecting it, but can't recall them now. Nevertheless, through the ages, you will see them brought up time and again, in renewed form as with Mowgli, Tarzan, etc.
Building off of Romulus and Remus would be Jason Grace from the Heroes of Olympus series. He, too, was brought up by the she-wolves. I haven't seen this trope anywhere else.
The Human Protagonist being raised by Non-human (Humanoid) Characters. Atalanta Tarzan The Faraway Paladin Sodatechi Maou! / Raised by the Demon Kings! The Summoner Who Was Despised as Shunned Child The Peaceful Travel Diaries of the Boy Raised By Holy Beasts ~Enjoying My Slow Life With My Friends Using the Cheat Magic I Received From God~ The Wolf Child Sora in the War Zone Nicola Traveling Around the Demons' World Lonely place, but I am here / A Country Without Humans