Thinking about @Ondath 's OP question a bit, I thin 5e would look very different if it truly embraced the type of modularity suggested by Monte. The trick is to design a very rigid system that allows things to be plugged-in or pulled out while giving the appearance of things working different...
To answer the OP, I can't imagine it would be an issue to make the Black Spider a title rather than a specific person. Tying to a player's back story might be a bridge to far tough. Let your player control their backstory, not you.
PS - Evidently it would be a good idea to make him tougher too...
This is the fourth or fifth answer that doesn't address the question in the OP and instead provides an answer about making the character tougher? Are people just reading the headline, making assumptions, and then answering without reading the OP?
Have you spent much time on the internet, or these forums specifically? If so, you had to know tangents would take over.
Particularly with this rather difficult topic. I mean, you're asking us to consider how to design a game that would provide the modularity to not only emulate all editions...