We don’t believe in original sin in the same sense that all people are born with sin that has to be cleansed by baptism, which is what I’m given to understand most Christians believe (I could be wrong, I’m not exactly clear on all the points). No one knows what the result would have been if Adam and Eve had not sinned, so maybe they would have died and maybe they wouldn’t. Some Muslim philosophers have proposed that it’s not clear that God intended Adam and Eve to dwell perpetually in the Garden anyway and that if they had resisted temptation they might have been able to come and go from the presence of Allah and the earthly realms like the angels. It’s just not a very relevant point of the story for us, so it isn’t much addressed. Clearly they did sin. We believe that capacity existed from the very beginning so that mankind could choose God instead of sin, and that there is no corruption in mankind that followed as a direct consequence of Adam’s choice. Everyone chooses their own corruption and everyone chooses to seek redemption as individuals.
In regards to sensual pleasure, since God made mankind to enjoy sensual pleasure and Heaven is a place where all pleasures are purified and permissible, then there will analogous pleasures in Heaven. If angels are made capable of experiencing sensual pleasure, then perhaps they do, too, but that’s really not relevant for us to know so it’s not all that important.