Except you've got the order of Captain Steele kind of backwards. Dead Dad therefore MC, because you're literally Victor's designer baby who was born to be his one legitimate child and the entire character creation is Victor deciding what he wants his future heir to be like. There's no agency on Captain Steele's part in this and the motivation that drives them throughout the game is provided to them by virtue of their origin as Victor's designer heir plus the Gaming Gods declaring that yes, you will be interested in finding all the probes and not just going out and having hot sex and unrelated adventures.That "and then" would explain how the Champ looks less proactive than Steele, at the start.
The only functional difference to how the protagonists are made is that TiTS provides a framing story for the character creation while CoC2 does not. I suppose it could be rewritten to start with you sitting down at Garth's and reflecting on your past as you're talking to him but that wouldn't substantially change anything. Once you've got your Champion, the tutorial gives you what will be your motivation for the rest of the game as a consequence of your actions as opposed to having it given to you before you were even born... or you can ignore Cait entirely because muh player agency, and then enjoy your premature end to the experience.