"Sie sind Menschen, und zugleich auch wieder nicht."
@a.xiao94 So do I. Some of them seem almost like idioms and there's no way to accurately figure out what they are from the definitions given. It would be helpful if more literal translations were provided, and then the idiomatic meaning were given also. If I think my answers are even in the ballpark, I'll usually submit them as possible answers.
The word ‘wieder’ in this context doesn't mean “again” in the sense of “another time”. After all, “at the same time, another time” doesn't make sense temporally. Here the word ‘wieder’ is used metaphorically, in the sense of “on the other hand”, for which English actually has a phrase containing the word “again”: “but then again”. So you could say “They are people, but then again, at the same time, they're also not.”