I would replace it with white wood rails/balusters.

Simple wood spindles.

You may reject this as somewhat off topic, but the most cost effective thing, I think, would be to replace the broadloom with hardwood flooring the railing will look pretty good afterwards (and anything else you do to the railing before then still won’t quite work).

IMO a new wall color would be the easiest and most cost effective update.

Screw a wood hand rail to the existing too-small top rail.