I’m not an expert but they look too “clean” to me. I suspect that they might be museum replicas such as: https://coinreplicas.com On a positive note: Your wildlife art is delightful!
Be careful. NGC does not guarantee authenticity of ancient coins, you know that right? I would guess this could be an issue if you ever tried to enforce this. A seller very well could claim NGC is not proof since they specifically state on their website that they do NOT guarantee an ancient coin is authentic.
I'm no expert, but I've looked at many ancient Greek coins, and all of them look off to me. Not because of the design necessarily, but the surface.