My knowledge on it is pretty basic, but as I understand, house spiders are adapted to living indoors: climate, food supply, and so forth. It's probable that over time spiders adapted to live in caves or tree hollows probably found it quite easy to move into dwellings, and stay there, to the extent that now some species have their entire life cycle based around dwellings.

[Edit: I googled around, and this was an interesting article from Rod Crawford, the curator of arachnid collections at the Burke Museum of Natural History & Culture, Seattle talking about house spiders being traced back to Roman times. https://www.burkemuseum.org/collections-and-research/biology... ]