In wa-kam bi-l-Qanān min muḥillin wa-muḥrim, kam does not ask for a numerical answer. It is exclamatory/declarative kam, indicating abundance: many people and circumstances have passed through this place.
Muḥill and muḥrim take the form of active participles, using a lexical contrast between ḥ-l-l and ḥ-r-m. The coordinating wāw holds opposite states together. Thus a geographical landmark becomes a setting with a human past.