Would the world be better if all races just separated?

That would be segregation all over again. Seperation is not the key. That would be like running from the issue. Facing it is the only way that can fix it.

Talking about 'races' is a tricky subject, especially in this era of 'Politically Correct.' I will say this though. Hitler and the Aryan Racist gang got it all completely wrong. The more we learn about genetics, the more it becomes clear that a Healthy Gene Pool means 'mix the races as much as possible...!' The more they are mixed, the greater the survival chances, because each 'race' or ethnic group brings its own unique survival history to the table and gives that added advantage against all those plagues that inevitable come down the pike, and come they will. Each different group survived different diseases and left an immunity trace in their particular genes. So, clearly, mixing groups also mixes the immune systems and immune history. There's a beautiful example this in Africa - the Cheetah Population. Seems they barely survived a terrible plague which almost wiped out the entire species. The few that survived were a very limited gene pool. They were suffering from what is called in genetics, a 'bottleneck' of limited survival and they were mating with close cousins and even sisters and brothers. Conservationists moved small pockets of Cheetahs all over Africa to mate with far distant population pockets and they began to make a small recovery, though they are still in great danger. One big plague can still wipe them all out. Still, and all, the lessons are quite clear. Mix the genes and mix that races as much as possible. Multiple immune systems can be the key to long-term survival.

How do you determine race? Culture? Geographical placement? Language? The amount of melanin in your skin? You first must CLEARLY define race as an actual thing- which cannot be done. You must understand that people may have the same skin tone, but vastly different cultures. There is only one race, the human race. This makes the question irrelevant.

people will always fight , there's not much u can do about that .

Well to start this would never happen and it would be seen as discrimination and racism even if everything were split equally. There is no reason to do it - most people these days accept every race and to be honest I dont think it would end our problems, probably just make it worse

Yes, only problem is the blacks would die off unless the others came to their aid.