You've got moisture issues. Beyond just a moisture barrier on the slab. You need to find out why you're having such moisture issues. Like the soil grading changed and is no longer directing water away from the house, or a gutter or downspout is clogged. Or isn't directed away from the house.

You've got to figure all of that out before even thinking about flooring. That's going to involve some in person investigating from you and from someone experienced in dealing with those issues. You might consider hiring a structural engineer to figure out where the problems are coming from, and to what extent they've affected the integrity of the home. That will let you create a plan and figure out what needs to be done by professionals.

Maybe a small seaping leak in the plumbing somewhere. Not all that unusual for a pipe to be leaking in/under a slab.

Otherwise possibly rain leakage. Check roof/attic if possible.

Nick, are you still here? Which model, the Shenendoah (3 BR) or the Tred Avon (4 BR, detached garage)?