There are a number of things that could be defiling his life.

1) Having to deal with not necessarily Jesse himself, but all the effects of it (having to explain to the other children that “the retard” they were wondering about is his brother, losing his childhood, etc.)

2) His parents (rather father and stepmothers) divorce ruining his childhood

3) Life itself ruining his life (if that makes sense). To
rephrase it: the hardships of life defiling his life

Billy Corgan was actually quite the athlete as a kid. When he would play basketball after school with the other kids Jesse would sit in the sandbox and watch him

It’s said that Corgan used the term “Spaceboy” because Jesse loved things that had to do with space.

The term also alludes to the idea that his brother’s mind seemed to be lost or that he was spacey. As Billy told Rolling Stone:

[Jesse] was raised to be a normal boy, but, of course, not everyone in the world sees him as a normal boy. Hence my song ‘Spaceboy,’ on Siamese Dream, because here’s this kind of kid who comes from some other planet and he’s had to figure it out for himself as he’s gotten to be a man.

Jesse is on Billy’s mind constantly as he acted as his caregiver from a very young age.

These lyrics either refer to A) Jesse’s physical disability or B) The stress of being so young and having to care of a brother with mental and physical disabilities

An oxymoron. Something that is “by the skin of it’s teeth” is rushed and barely made, but if it with timing and class then that means it was planned and organized.

This might refer to the conservative media outlet Fox News. To the band, it seems that right-leaning viewers look to it as their savior and use it exclusively to form opinions. In an interview with the New York Times, Chris Martin shared:

The band wrote the first line and the first little melody of the song years ago, but didn’t finish it until last year. One day I was watching Bill O’Reilly, and I was like, ‘I know how to finish that song.‘ My best friend, Tim, he’s a musician in a band called the High Wire, but he also has to work in a bar. He was having trouble with his boss, and it made me think that so many people spend their lives being told what to do by people that they just don’t like. So it was that idea, and watching Bill O’Reilly, and all these words just came out.

It is often believed that Martin says “fog” instead of “fox”, but this was proven to be wrong. Indeed, it can be clearly heard in the concert footage below that “fox” is the correct lyric.

“Carnival of idiots” is a common way of describing politicians when they put on their “shows” of indignation to the public, but all real decisions have been made behind closed doors. The narrator claims that these groups manipulate the future by telling people how to feel instead of presenting facts.