Dictionary word used by business but not copyrighted. Safe to get the domain?

Lets suppose a socks factory is created and they choose the word "BANANA" to design their business. It is a dictionary word.
But they didn't bother to copyright the brand anywhere.
Lets suposse years later the domain banana.com is still available.
Lets suppose i buy it.
Later the factory decides to copyright their brand BANANA. (banana socks or just banana i don't know).
Would this be a concern for me?

Now lets get more difficult.
Lets suppose the same case but with a small…

Dictionary word used by business but not copyrighted. Safe to get the domain?