We just installed some lose lay flooring
I had that in my Burro
when I bought it. I changed it out because I didn't like the pattern.
It came up very easily, and yes, it could have just plopped back down in there.
There was a thin layer of condensation type moisture under it, and on one end, in the front where water had rolled off the walls, the floor was wet on the surface plys.
Fortunately, the damage was not bad enough to have to replace (I dried it out for a couple of days) but it really made me skeptical of that type of floor. Dirt and stuff was under it too.
I put down peel and stick "wood" strips. Looks like wood until you get your face down in it, and I am sure the adhesive will provide protection from moisture.