From what I've gathered reading these forums, it appears that the storylines make more sense and are potentially more engaging if you chose certain origin characters and are able to loosely follow Larian's intended path for you.
Now, there will be people who claim that these things do not matter -- but as you've already observed, the writing and coordination of events and dialogue can unravel if you go too far outside the lines.
One bit of caution, though, and this was just my experience: When I started out, I thought "The combat is horrid, but I'm interested in seeing where these characters go and what the main plot reveals itself to be." Once I got those answers, I realized that the worst part of BG3 - for me, at least - was the writing.
Your experience may be drastically better, of course -- just a warning that if you don't like what you've seen so far I would wonder if you're going to love what comes later. Hopefully, it works for you. Good luck!
