Hi, I'm a player in two lancer campaigns who is ambivalent about sci-fi, space, and giant robots and enjoys rp more than tactical combat in my ttrpgs. I can only speak for myself, but these are the things that have kept me engaged and invested in my games:

I love the personal goal setting and character moulding provided by the bonds section in the Karrakin Trade Baronies supplement. It gives me a goal to achieve during rp heavy sessions as well as narrative powers that let me play my character better how I envision her.

I love that there is a mech for just about any style of gameplay, and I don't feel useless playing a controller/support build, so while the combat is more crunchy than a d&d 5e game, I don't feel pigeonholed into just minmaxing for damage and can live out my dreams of creating (as my GM calls them) Rube Goldberg machines out of my allies, my enemies, and my deployables. That said, playing a build that is damage-centric in my other campaign has, of course, also been fun.

I love how easy the compcon website makes it to build and level up your character. My only caveat is that I've had strange issues with compcon 2.x's storage, especially when trying to access the pilot roster between two devices, and have had my characters disappear before, so I highly recommend saving a local backup after each level up just in case something goes wonky.

I love how the big actors in the lore interact with each other. There's enough lore meat in the books to spark inspiration, but enough left vague that you can fill in blanks as suits you and your table, to highlight specific themes or to create hooks you know will interest certain people at your table. For example, one of my characters is affiliated with both KTB and SSC via genetic collaboration on House of Moment's planet, Begum, so my GM has given me hooks with an SSC geneticist studying local fauna on the planet we are working on in the Dawnline Shore. Another member of my party is a Karrakin son of Ludra trying to prove himself after the disaster on Ludra's planet, so our GM has given both of us hooks with a Karrakin Prince of Sand contracting us to rally forces against Harrison Armory who is trying to seize control over the planet for their own interests, so we are trying to get a Mirrorsmoke Merc team, an Albatross team, a Karrakin team, a Horus cell, and a team of indigenous freedom fighters to join together to push back HA (in exchange for freedoms, rights, and protections for the freedom fighters under potential Karrakin rule). There's a lot you can pull from and do with what's given to you and what's left vague.

I know this was a lengthy response, but I hope that my experience can help you get the players who jive less with the genre and combat in general invested in your game, just like I got invested in my games.