hard to say tbh. it might be easier to put a pin in if we knew why your investment isnt sticking or what youre getting from the game vs what you expected from it

for me half the fun was making a tav and building out their backstory and personality, and figuring out how to fit that in with the story and the choices i was given.

you could be lacking the same emotional investment in your tav. maybe youd prefer the loose framework dark urge gives you, or maybe youd hate how dark and edgy it gets. maybe you should try playing your favourite origin companion instead. maybe you just dont like the specific crpg mechanics of bg3, or you dont like how bards play.

Strongly suggest not to Durge unless you've done a playthrough already.

BG3 has a lot of ways to play and diverse choices (had no idea you could confront Kagha in the swamp!) so if you're not feeling it, you can basically play an entirely new game if you want by trying again. That said, I also personally struggled at first, but fell in love by the time I'd been through a few quests and picked up all the party.

all of the above is solid advice! i def recommend picking your favorite origin who isn't dark urge and going with that. save durge for another playthrough, since you might have some of the same issues of disconnect with a basic tav. all the origins get fun cutscenes and story beats unique to their history and characters, so try that!

dont be a pussy play durge the same way you'd play disco elysium the first time through like i did

seriously: there's no "wrong" way to play this game, whether its the first time or fourteenth. they put the origins in there for a reason, right? i know they recommend not starting with durge and i can definitely understand why, even as someone who did (and then replayed durge before playing a regular tav) but it's not Incorrect because of that.

if you're having trouble connecting to your tav, you can always retool around with background, race, and/or class - each one gets unique options in dialogue here and there which does help fill things in! it could just be the race or background you've got now don't vibe with you.

i WOULD recommend against playing one of the companion origins for your first go though, just because you lose all of the acting and 'organic' nuances/growth of the characters.

otherwise, the origin vs tav doesn't matter too much for the general feel of the game, honestly. it could just be the order/way you're going through things, or other various gameplay things. please, please, please long rest, and long rest often. you will not get timed out of quests unless it is made ABUNDANTLY clear that it's "you have until tomorrow" or something. the only thing not long resting does is make the game harder and makes you miss out on story content!! i made the mistake of going "no time is clearly pressing and long rests are a sparse resource" my first time and missed so much. second play through i would legit have times where i was like "huh, wonder if there's any more story beats" and rest 2-3 times back to back.

the game feels REALLY empty narratively if you don't long rest, because much of the interparty plot progresses with long rests. please long rest. please long rest.

I haven't looked too deeply into this for illithids, but I used this mod for other NPCs to replace my Tav with them. You'll need the cheat engine to get it to work though.

https://www.nexusmods.com/baldursgate3/mods/1163

https://www.cheatengine.org/downloads.php