This has happened to so many people so don't feel bad haha. I think it was particularly common with people that got the game when it came out, then got brought back by some sort of new season offerings, and didn't even realize they were skipping the entire story, exactly like it is for you.

I think it would be best for you to get back into the story because honestly, after 150 hours of playing this game I know that people are really gunning for endgame stuff that have been playing it for years, but for new players you can't really participate in that sort of thing like the grizzled veterans can. Also, the story in D4 is IMO the best Diablo story they have ever told. As someone that normally skips all cinematics in almost every game, I watched all of these because they are seriously well-made.