Guidance needed wiring in a smart light switch. The wiring in this box is making me question what little I knew.

Hello. I’m attempting to switch one of the switches out in our home and want to make sure I understand the wiring correctly before jumping into it. I’ll preface this by saying I have no formal electrical training but have a general understanding of basic electricity and wiring (I think).

The box has 3 switches inside it but I have 5 strands of romex coming in. Each strand has a black (hot), white (neutral), and bare copper wire (ground). My understanding is that one of the strands is the line side coming in delivering the electricity from the breaker box, one strand probably connects to a different switch (there’s a nearby switch that is connected to this same breaker), then the other three strands go out to the individual loads for each switch.

I had to make a crude drawing to wrap my head around what was going on inside this box.

Based on my understanding, I would take one of the black leads on my new switch that say Line/Load and connect one to the wire nut bundle of black hot wires and one to the black wire that was attached to the original switch. Then I’d attach my white neutral to all the other neutrals and the green ground to all the other grounds. Does this sound right?

Sorry if this is a dumb question but trying to follow all the wiring chaos inside this box had me questioning if I understood wiring principles as much as I thought.

Thank you for any advice!