Maybe it's a cartoon in a fairytale setting and the horns give the boy some special powers or make him stand out. Or perhaps it's a story about a creature that looks like a boy but has horns.
Since we don't know the exact 'boy with horns story', it's hard to say. But it's likely the boy with horns is the main character.
Maybe the guy's action of making deer horns violated some important rule or caused harm in the cartoon world, so the character shot him.
It could be a tale of a mischievous little demon with horns having adventures in a fantasy world.
The main character of The Old Man and the Sea, the old man, was called santiago. He was an old fisherman from cuba. After a tenacious struggle with the marlin, he finally caught a fish bigger than his boat. However, santiago did not bring the fish back to the city, but continued to swim to the end of the sea with it. The little boy was called San Diago. He was the grandson of San Diago. He joined San Diago's fighting activities in order to learn fishing from his grandfather.
The deer boy cartoon usually has cute and vivid character designs. The storylines might focus on adventures or friendship.
If the protagonist was a little boy, the novel might involve children's growth, adventure, magic, and other elements. Such novels often depicted the protagonist emerging from an ordinary life and gradually growing into a powerful character, facing various challenges and difficulties. In the story, the protagonist might make all kinds of friends and grow up with them. Such novels might also have mysterious magical elements that allowed the protagonist to gain more strength and wisdom as he grew up.
" Primitive Age " was a novel about a game. The main character was a little boy who lived in the Primitive World. He had to grow up in order to deal with all kinds of crises and challenges. I hope you like my recommendation.