In Paine's opinion, all people are born as equals. But that doesn't mean they should stay equal their entire lives. Some people rise in the world and some people fall as a result of stuff that happens after they've been born, like working hard, or hardly working.
But there is no reason at all for the division between a King and his subjects. A King does nothing to earn his role as King. He's just born into it because his dad was a King.
To make his case against kings in general, Paine takes us way back to the earliest stages of human existence, when there was (according to him) no such thing as kings. And because there were no kings, there were no wars either. That's because the only reason wars happen (again, according to Paine) is because kings start talking smack at one another and then send a bunch of soldiers off to die in order to show which king is more powerful.
Like many people during his time, Paine unfortunately (and wrongfully) blames the Jewish people for ruining the modern world.
He claims that Jewish people were the first to copy the "Heathen" practice of having kings because they were lazy cowards who wanted someone to tell them what to do.
On several occasions, the people they wanted to be king told them "No thanks. I don't wanna be king." This is because God is the only person with the power to rule.
Over history, though, the Jewish people kept pushing the agenda. They didn't just want one person to be king, though. They wanted all his sons to be kings forever, too.
And that's how the idea of inheritance came into play.
According to Paine's reading of the Bible, the Lord Almighty punished the Jewish people for trying to create a human-god by turning someone into a king. Thus, the Bible is firmly against the very idea of someone being a total ruler. And, uh, Jews presumably? Where's that famous common sense now, Paine?
For Paine, the idea of a king isn't so bad on its own. It's the fact that every male descendant of that same family will become king just because they're born into it. Paine insists that this system has given the world many more terrible leaders than good ones. Ok, Paine's common sense has reappeared. Phew.
Even England itself was conquered by (the appropriately named) William the Conqueror, who was actually French. Ever since then, it's been the descendants of a French dude who have ruled over the nation. Paine doesn't see why people would continue to honor the descendants of a brutal lunatic, especially one who isn't from England to begin with.
Another terrible thing about having kings is that kings can sometimes be extremely young or extremely old, which leaves them vulnerable to being brainwashed by any crafty servant or advisor who has their ear. Shades of Iago?
In some cases, kings don't actually do anything at all for their countries. They have no political responsibilities apart from attending ceremonies and living off the wealth of the people.
So where are all the good, decent kings? There are none, because good, decent people aren't rewarded by ascending to the position of kings. Only the sons of kings become kings.