[jhynesrockmtn]

If nothing has been done to seal that wall, at a minimum it is wet on the outside with some moisture leaching through the concrete. It may be dry on the floor, you may not see water, but it is there. I would investigate further with a quality moisture meter and take some humidity readings over a few days, hopefully with some rain falling outside. I just noticed the Seattle in your signature. The rain part is easy. I owned maybe 10 personal and rental properties in the greater Seattle area over 30 years, several in Seattle proper and built in the early 1900's. It is really hard to have a true dry basement in an old house in Seattle. My 40s era house in West Seattle was the dryest and was a walkout in the back. If just storage, use something that doesn't hold moisture to keep things off of the floor and seal stored things appropriately. Should be fine. If you are wanting to build out the space into living space, more work may be needed.