Many brands are existing words. You don't even need to look at edge cases to support this:
* Apple
* Amazon
* Nike
* Oracle
* Visa
* Fox
....
The point of trademarks is to protect consumers from misleadingly identified products. Whether the word is used for something else is irrelevant. Basically all western countries take into account the context in which the term is used. i.e. your grocery store can still legally sell a fruit called 'apple'.
* Apple
* Amazon
* Nike
* Oracle
* Visa
* Fox
....
The point of trademarks is to protect consumers from misleadingly identified products. Whether the word is used for something else is irrelevant. Basically all western countries take into account the context in which the term is used. i.e. your grocery store can still legally sell a fruit called 'apple'.