This is one of the most powerful films I have ever watched, also one among the few Lynch movies which uses a linear narrative, with no utterly confusing dream sequences.
The movie is based on the real life story of Joseph Carey Merrick. In the movie, the character is named John Merrick, probably because, many sources mistakenly refer to him as John instead of Joseph. He is a severly deformed man and consequently ugly from the viewpoint of most of the people. For the stalkers, he is a spectacle, an object of pity and disgust which externalizes the ugliness within themselves. As many of Rainer Werner Fassbinder's films suggests, human relationships thrive on exploitation, this movie portrays how the weak is exploited by the meek and the ruthless. Merrick is 'exhibited' under the section 'freaks' in carnivals. He is owned by the character named Bytes and he calls himself the owner of Merrick and proprietor of the show.
The character of Dr. Frederick Treves (again based on the doctor who actually treated Joseph Carey Merrick, is played by Anthony Hopkins. It is one of his most powerful performances IMHO, the another being Othello in the BBC Shakespeare Series. The doctor, though becomes Merrick's friend, ends up being regretful for using Merrick as his subject. One is also reminded about the eternal misery that some people have to endure, because pretty much nothing changes for them, but the settings. Merrick becomes a spectacle for the upper class once he is shifted to the hospital under the care of Dr. Treves. As Bytes says to Treves during their first meeting, 'We understand each other completely!' This points to the later stage of the movie where Merrick would continue to be a spectacle under Treves.
Many people enjoy being in the limelight. But in most cases, there is bound to be a mismatch in the reasons why the audience is interested in a personality and how (s)he wants others to see him/her. The fact remains that (most of the) people do not want to admire the strength of a person (if he is beyond their reach). But they would like to look at the weakness of a person and perceive their very weakness in the celebrity.
John Merrick does not mind the attention, but his only need is to be recognised as a human being instead of a monster. And he carries with him the unfulfilled desire to be loved. Towards the end, he finishes his work on the cathedral made out of cardboard and embarks on the inevitable journey to the unknown land.