Without having read the novel, it's impossible to name the main characters accurately. But we can make some educated guesses. There could be a central character, let's call them Alex, who is one of the 'children of Jupiter'. Alex might be an ordinary person at the start, but as the story unfolds, discovers their extraordinary abilities. There could also be a scientist character, Dr. Smith, who is studying the 'children of Jupiter' and trying to understand their origin. And perhaps a villain, Mr. Black, who wants to use the 'children of Jupiter' for his own evil purposes, like taking over the galaxy or something. But again, this is all speculation without actually reading the book.
Since I'm not familiar with this 'Children of Jupiter' sci - fi novel, it's difficult to say exactly who the main characters are. But if it follows typical sci - fi tropes, there might be a group of diverse individuals among the 'children of Jupiter'. There could be a brave and curious protagonist who is on a journey to discover their true identity and purpose. There might also be a mentor figure, perhaps an older 'child of Jupiter' or someone from a different planet who has knowledge about their heritage. And then there could be antagonists, like those who oppose the 'children of Jupiter' for some reason, perhaps fearing their power or seeing them as a threat to the existing order.
I don't know as I haven't read it. It could be the 'children' themselves, whoever they are. Maybe there's a leader among them who has special powers or knowledge.