Depends how you define improvement. Technology would still boom maybe even more so, but society and culture would remain mostly stagnant. People's beliefs rare

Depends how you define improvement. Technology would still boom maybe even more so, but society and culture would remain mostly stagnant. People's beliefs rarely change. It's the younger generations that further define culture and bring change. The older generations strive to maintain status quo. Thought experiment: In the past people openly discriminated against lgbt people. Today LGBT rights and acceptance have won (and will keep winning)! It's not the racist old uncle that thinks it's a disease, that incited that change. It is the newer generations that first learn everything their parents know, and then they learn from their parents mistakes. As time passes the balance of acceptance shifts and a societal shift has occurred! Now of course, this doesn't mean that old people are evil, or incapable of change, or that everything will be perfect because each generation is always better. This only means that this is one of the ways change can happen. In a world of immortals, only violent uprisings could challenge the status quo. The world would have no incentive to change. If 100 years ago everybody suddenly became immortal and sterile (no deaths/no births), would the world of today have still invented punk rock? Answer's no (not without youthful rebellion)