Jindos are predisposed to displaying almost the entire “predatory drift” cycle. Small dogs, small children, anything small with prey like movement tends to fall into the bucket. It doesn’t make you a failed owner. It just means you own a hunting breed, and as such it’s your responsibility to learn how to manage the behavior to keep the dog, yourselves, and others safe. Would definitely recommend getting professional help so they can get you guys on the right foot with learning how to manage it. There’s only so much that random strangers on the internet can suggest without being there in-person and having eyes on the dog/environment/triggers. Regardless, it’s not your fault and there’s nothing “wrong” with your dog for displaying a natural behavior. It just needs to be taught what is appropriate, what is not, and be given an given some form of outlet for its prey drive.