You are right that for any interplanetary human expedition a prerequisite is to be able to make a closed environment for humans, where carbon dioxide, water, food left-overs and almost all other waste products generated by humans are recycled, producing free oxygen, potable water and food.

However, this does not mean that other required technologies, like for transportation or for protection against dust, cannot be solved before.

I also agree that recycling technologies are actually more important than spacecraft technologies, because they are equally applicable on Earth, not only on the path to other planets or in bases established there.

I do not believe that interplanetary travel will be possible for humans otherwise than in spaceships with artificial gravity produced by rotation.

This not only would avoid the health problems (the experiments on mice in the ISS imply that a gravity as high as 2/3 of that of Earth might be necessary for preventing harmful effects during long-term missions) but it would also simplify many of the recycling technologies, because handling fluids and powders is difficult in weightlessness. It would also simplify the growing of plants or fungi.