These brands are not distinctive enough because they can describe something of the product beef burgers. For example how they taste (tasty) or what kind of meat they are made with (Black Angus Beef or beef in general).
A brand must comply with the legal rules in order to be registered. In the Benelux and in many areas and countries outside the Benelux, a brand may not be descriptive or misleading (for example, “veggie burger” in a brand name for beef burgers) and it must have sufficient distinctiveness.
Brands that do not comply with these rules will email leads be rejected by the official bodies of those regions or countries.
What is then a distinctive example for a brand name for beef burgers? “Jan”, “Black rebel” and “Palmboom” are brand names that are sufficiently distinctive. They say nothing about the product “beef burgers” and are not misleading.
Do you want to be sure that you have the right to your brand and the value it represents? Then you need to register your brand. You investigate whether your brand is still available and check whether it is sufficiently distinctive. Because only then will you have a strong brand.
To search for the availability check in the Benelux trademark register, search in the BOIP trademark register. BOIP is also the official body where you apply for a Benelux trademark registration.
If you would rather not do this yourself or need advice on whether your brand meets the requirements, find a legal professional in this area.