Modern physics is well beyond the point where I, as a layman, can really understand it. It still doesn't make sense to me how gravity is put in the same bucket

Modern physics is well beyond the point where I, as a layman, can really understand it. It still doesn't make sense to me how gravity is put in the same bucket as the other three "fundamental" forces. Since the universe is expanding, are we making more space (or spacetime)? If so, how does that work? I'm not even sure if the universe is finite or not. I mean the observable universe is but how that relate to the actual universe? This seems like it would be somewhat unknowable. Honestly, I'm still fuzzy on what the Higgs boson is and does and how it seems to be this redheaded stepchild in the Particle Zoo that doesn't really fit it anywhere else. Speaking of the particle zoo, why are there (generally) three generations of particles/ The article touched on this but is space and/or time discrete or continuous? I'd learned that there was a concept of Planck distance, being the limit of how small a distance you could have. But is this the quanta of distance or just a limit on how low you can measure? Is it just me or are we in a drought of theoretical physics breakthroughs? When I was younger, I guess I imagine we'd not be in the same position we were 20+ years ago. I mean there have been advances of course but we have things like the LHC pretty much confirming everything we already knew. Even the Higgs boson breakthrough was confirmation of a ~50 year old theory. A bunch of contender theories have been disproven, which of course has value. But it seems like we're really no closer to reconciling quantum mechanics and gravity (other than eliminating candidates).