Weak or Not

I believe in Theory Karl Marx's "survival of the fittest" and "natural selection" would only work. It seems rational to think that only the strong should survive and the weak should die off however, in the case of the proletariat and bourgeoisie   classes I believe it is inhumane. I believe we as humans hold the responsibility to be compassionate and loving to one another. Animals have no rational way of thinking, however, we do. Allowing the weaker or financially challenged class to die off would make merely animals. I believe Marx should also consider that everyone doesn't start off with the fairest chance to survive and we should not hold these people accountable.
Marx should try to think of a system that is based off of a "too bad you are not fortunate enough mentality". During this time period the gap between rich and poor was sickening. People were dying on the streets from starvation and disease . Many of the people who were struggling were working for these upper class employers. The employers did not even provide enough wage for their employees to live comfortably. If Marx's theory was to work, I believe people should not have intentionally  made the "weak" situation worse. Overall, its disgusting I believe in the condition of the time period, the strong should have not been defined as strong. They should have just been defined as people who have an advantage, and the weak should have not bee defined by just weak.