The sentence "In her prime, Henrietta herself stood only a bit over five feet tall" suggests that Henrietta, at the peak of her physical condition, was not a particularly tall person and measured just a little over five feet in height.
Without more context, it is impossible to know exactly which Henrietta is being referred to. However, it is likely that the sentence is discussing a specific person named Henrietta, rather than using the name in a general sense.
It is worth noting that height can be an important factor in some contexts, such as certain sports or military roles. However, in most cases, a person's height is just one aspect of their physical appearance and does not necessarily indicate anything about their abilities or personality.