First of all he's completely bipedal. This isn't unheard of in Pokemon. Blastoise is bipedal. Even Pikachu is bipedal sometimes. The difference is they're not as skilled at it as people. Cinderace stands completely upright like a man though. Not only that, the way he manipulates his legs and feet when he does his kicks is distinctly human. Plenty of Pokemon stand upright, but they usually have large tails for balance like Mewtwo, or strange posture like Mr. Mime.

Of all the humanoid Pokemon, Cinderace's proportions look the most realistic to me. In the anime he looks like just another human hanging out with Ash and Goh. His arms, legs, and torso are designed in a similar style to humans on the show. Even his large feet match the current art style they've been using for humans. Pokemon like Incineroar and Intelleon look at least like cartoonish people with exaggerated proportions. Not the case with Cinderace. The only thing he's missing are hands, and his tiny paws don't mesh with his design. They look like amputated limbs to me.

We're supposed to think of Pokemon as being like extraordinary animals, but Cinderace looks like a man to me. It doesn't seem right for him to live in a Pokeball. He has a flat, round face like a human. He stands upright with fully developed legs. He's sentient. The only thing he's missing is speech. There is such a thing as "the uncanny valley." I don't have anything against anthropomorphism in Pokemon, but Cinderace comes too close to being human and it's unsettling