How to fix stained unfinished floors?

I moved into a house where the primary bedroom floors are unfinished and have a ton of both large bleach spots and dark stains. What is the best way to remedy this? Should I put a dark stain over it? Is there something I can coat it with to make it waterproof? I've also been reading about LVP install without using adhesive. (I have no experience)

Open to all suggestions and thank you in advance!