It generally refers to a group of “normal” people. E.g in some context they are an “out” group that does not have some specialized knowledge or understanding that the “in” group would have. So it can be negative, but it generally just means someone inexperienced with the given topic area. There is an implication of otherness to using the term “normie” for the group using it but it is generally a pretty common term now. For example, imagine a bunch of policy wonks debating something in highly specific language and then someone asks “how would the normies react?” They mean, “how would people unfamiliar with the inner workings of political policy react?” Stuff like that.

It does have a negative connotation for that group in some contexts, but the usage is pretty common and softened now.