i don't want to live in a world where death is no more. No more than a fleeing moment and yet so devastating.

 i don't want to live in a world where death is no more. No more than a fleeing moment and yet so devastating. 

When the line is crossed, man will be filled with profound feelings of fulfilment. Humanity's long relationship with death and immortality will finally reach its conclusion. They do make up in the end but their relationship will never be the same again. 

Most definitely, immortality will not be for everyone. Decades might pass before it is accessible to whoever wishes to overcome the possibility of natural death. The technology/procedure{?}, will be standardized by then and the operational costs will be at their lowest level. The hype from the techno-bourgeoisie will finally settle down and the masses will be allowed to access it and the multinational to profit from the working classes. 

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How much of a difference does it make if the solution to death allows humans to reproduce themselves without any consequences? Would more people go for it?

Let's say immortality is normalised and humans do/can not reproduce and the last of us (the immortals) eventually kill ourselves at a peak of a never-ending existential crisis. Ghosts of the dead will haunt our dreams longing to be in our shoes. It may naturally be that to find peace with the dead one must reproduce and preserve humanity.  

agri culture

 How could a group of humans living off their hunting and gathering ventures, develop the cultivation of land or agriculture and the domestication of animals?

Could it be a pot filled with water with a single leaf placed inside? Forgotten in time, slowly but surely growing roots out of it. And when the human observed the outcome, decided to experiment with the flora around and crucially, cultivate their source of subsistence?

Perhaps it is the fruit's remaining seeds persistently thrown around the group's occupied land when eventually, the newly-grown plants around them produced the same fruit.

Perhaps they had mushrooms visualizing modernity and later, they were just striving to fulfil it...

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I do not want to dwell in what constitutes the culture of agriculture but rather on the fact that agriculture implies some sort of culture. Since groups of humans developed some form of agriculture they have also developed a culture around agriculture. 

In other words, a culture can be observed and verified from the daily lives of the group at hand. Without the regular hardships of maintaining land and animals, agriculture wouldn't have developed. A day off can be fatal for the whole group. Thus, the alteration of the humans' daily lives to manifest the agri culture shows clearly how a culture can be established.

Whether in a social group or not, the actualisation of the cultural traits we wish to flourish lie on the individual. Of course, the manifestation or creation of a culture is better done with others but that doesn't hinder the responsibility of each one.