If someone watches all of your Instagram stories but don’t message you are they a stalker? Like there is not one time they skip watching my stories.

Maybe, but I wouldn't read too much into it. The way that instagram has stories set up is that you just go through them as they come up. It could be that he searches you, or that he was just browsing through your story out of boredom.
If he isn't messaging you, then he probably isn't interested in you as anything more than entertainment. You can mark your profile as private and he won't be able to view your stories again. You can remove him as a follower as well and then he won't see anything you post unless you let him.