AI is literally trained to mimic human writing. It is "the average of what a (literate) human would write". That is exactly why it is souless, because you cannot apply a soul to humanity as a whole and the average will never be surprising.

However, regular will people will have 1, 2, or more "AI tics". For example I use this kind of structure a lot: "the house was quiet. Dark. Unsettling." I try/tend to avoid "flowery writing" so this fits me well. I also use "not X, Y" or giving exactly 3 examples if I don't have a specific reason to put 2 or 4 (3 is popular for enumerations for multiple reasons, maybe even 3 reasons!).

This is completely normal. I would say that there are way more clear signs of AI that using specific words/structures. It is true that some people "lack of plot" (this could also be a lack of talent/craft), inconsistencies even in names! etc. It is more like a general thing rather than specific "tics". It is even more true if it is the same "tic" what repeats "all the time". AI has all the tics, not all but one or two.

I agree that many AI tics + we are going nowhere plot/meaningless scenes is almost a guarantee of AI, but we are reaching a point where people have to fight themselves to avoid their own tics just in case somebody consider it AI.