I personally could not sit still for story time. I find it boring as most of the time! As an adult I have the skills to make myself sit still for it if my child really wants to go but it's never been my kids cup of tea. They can sit still for lots of stories one on one and love being read to. But library story time is not for everyone if you ask me... On the other hand my eldest probably has inattentive ADHD, so maybe my idea of "normal" isn't very "normal"...
My 2nd daughter had no identified problems but it's taken 2 full years of preschool to learn to participate nicely in group time. She'd just prefer to be doing her own thing, exploring the environment (which is packed full of interesting resources). Although she's a happy and quite well behaved child she's not a people pleaser. She was never the child to do something purely because it would make me (or anyone else) happy. She will do something for a good reason though...
I am sorry if I have rambled without providing any useful insight.