Okay, let me go through all your points.
1. You say Leo and your OC share similarities. Pale skin, which you can't own, a headband and earrings, which he's had ever since I joined, and the same eyes/eyelashes, which may I add, he doesn't even have eyelashes and again, I can't copy you if that post never existed when I made Leo.
2. I made my OC way before you and others. They've been on my page for YEARS, so anything after that can't be copied. I'm not calling you an idiot either, but logically speaking, you can't copy something if it was made AFTER you made something. You have all the right in the world to complain, but factually speaking, it would've been impossible for me to know you would've made a post. I'm not a mind reader.
3. Originality can be seen. I don't own cat ears and pink hair, but when there's more than 5 traits I can point out that's similar in a character and the person follows me and comments, obviously, it means they copied.