So you can lose the “In an anthromorphic world” part (btw it’s anthropomorphic). It’s assumed the world you’ve created has some relation to people even if it’s shown through the eyes and actions of an all-animal cast. This logline is thematically unfocused and has no motivations, stakes or urgency to it, so it falls flat.

First question I’d ask: What are stakes if the young lion doesn’t succeed? Will his father disown him? Kill him?

2nd question I’d ask: How does “using their differences” help address the protagonist’s goal? Is the lion by nature unable to play well with other creatures and therefore missing a vital component in achieving success (ie, he needs diversity to succeed where he previously failed by staying with his own kind)?

“Battle against convention” is bland and virtually useless information. Why does joining a diverse sports team matter to the lion cub or his father? It seems like you have to find the core meat behind A) the sports team B) diversity and C) the father’s approval and love as well as the stakes (what happens if he doesn’t succeed) before you’ll find your story. Good luck!