"Can we live in peace?

In the ancient times people used to be violent and cruel with their neighbors – other people. They were greedy and angry because that helped them to survive. People who were the most savage had more food, fur and just had a better life than others had.
Times have changed. Now people do not need to be angry and cruel to each other, because all that they want they can be bought for the with money. But they still are (cruel). The reasons of the for most of the conflicts are our bad emotions like anger, greed, cruelty and etc.
People are different. Someone is cruel and angry because they are what they are. And we cannot judge them because that is not their fault. We must to blame the reason of their behavior, but it is impossible to find it now.
To get closer to the peace we must to change our minds and start to love and value what we have. All what that we need is just to always be kind.
To sum up, to live in peace is utopia. All that we have is a belief in people and their kindness. One day people will stop to quarrelling and they will start to appreciate each other but not today or even tomorrow."

A few notes:

If you are using all in a sentence, you don't need to use just as they have the same meaning in that context.

You are using what instead of that for relative pronouns, "what" is a determiner so it's better to use "that". for example:

"The things what I need"

"The things that I need"

situations where what is used:

"We photographed what little animals we could see"

Hope that helped! Overall you did a great job!