I have a Maine Coon kitten who is 1.5 months old. When he's playful, he starts biting and scratching whenever he sees your arm next to him, and any hand movement is like an invitation to bite. Trying to put a hand on his back causes him to roll over and fight it with claws and teeth. Same is with feet. He even purrs when biting. He never purrs when playing with toys.
When he's sleepy, he's nice and sweet, purring and allowing to be petted. He sleeps next to us, so he doesn't hate us.
Different internet resources divide into two groups: some say 'He's just a kitten, it's totally fine, he'll stop', and others say 'If I don't teach him not to bite, he'll bite all his life'.
We've tried playing with him with toys, tried screaming when it's painful, tried spraying with water once, nothing seems to be working really. At most, he switches to something else, and next time he wants to bite again, he bites.
So, maybe he's really too young to stop just yet? At what age they stop biting on their own?