What human experiences are portrayed in 1984 and what does Orwell suggest about the dangers of loosing such experiences?

The principal human relationship at the heart of the story of 1984 is between Winston and Julia. The love between two people, as basic as it is to human existence, is the very thing most at odds with the Party's "philosophy"—its requirement of the way people should act. The fact that even by "traditional" standards Winston and Julia are in an illicit relationship is an additional part of their "heresy," and it's ironic that in this sense the Party seems to be in agreement with the old, pre-dystopian world that has been overturned.
But the very idea of love and passion is antithetical to the Party's aim of controlling people and reducing them to the level of brute zombies. Love and sexuality are human experiences that threaten the dominion of the Party, and this is why the affair between Winston and Julia represents a form of subversiveness for which they know they will be punished. Not only is love an experience in danger of being lost in the dystopian world—it has already been destroyed, given the grim outcome that awaits Julia and Winston.
The same is true of the bonds that normally have existed between parents and children. Parsons, who on the surface appears to be the most compliant and unthinking citizen, is betrayed by his own children who overhear him uttering heretical words in his sleep. The Party deliberately trains children to have no love for or loyalty to their parents.
And even friendship between adults, in the ordinary sense, no longer exists. Winston likes Syme, but Syme isn't a friend so much as a person whose company Winston finds more pleasant than that of others. Syme, despite his intelligence, is a fanatical adherent of the Party. He has no empathy for others and enjoys the spectacle of other people's suffering. Though he's ultimately "vaporized" (as Winston has predicted) he represents the absence of human kindness, of feeling for others.
In all, the entire experience of what it means to be human is what the Party has succeeded in destroying.