Should husband helping with the kids be 50-50

This is up to the individual couples to decide. In most families the man earns more money than the woman, so that already creates an imbalance. It makes sense in cases when the man, say, is the primary earner to expect the woman to tend to kids more. It also makes sense in cases when the woman is the primary earner to expect the man to tend to kids more. Again, it is up to the couples to decide, but my view of a healthy relationship is one of that in which both partners contribute significantly.

There is also the factor that biologically women are wired to raise kids much harder than men; traditionally men would go to hunt animals or do something else requiring a lot of physical activity, while women stayed in the tribe tending to their kids. While such an arrangement is no longer the case in the modern world, biology is not so hard to rewire, and it makes sense for this imbalance to remain in the society, regardless of any discrimination.

People should separate social discrimination from natural inequality between sexes. This whole idea that men and women are absolutely equal in everything is wrong on many levels. It is important to appreciate biological differences between us; what is wrong is thinking that those differences must compel us to do something. But they must be appreciated nonetheless.
"Equality", the one human rights movements have fought for for centuries, refers to equality of opportunity, not outcome. What people fought for is lack of prejudice and giving everyone a chance. They did not fight for some statistical equalisation of what people actually choose to do in life.