Not far in the game honestly, just left academy and I'm fighting against prisoners in that jail district. But I just don't have motivation to continue. Gameplay feels kinda clunky and slow, only henchmen, no real party members, story feels kinda bland and dull. I guess I went in expecting too much of Baldurs Gate.
Are expansions more worth it? Could I just skip vanilla campaign and play them, or are they sequels to original campaign?

Depends what you are looking for. I can't tell what stories will work for you. I felt the OC improved a lot in Chapter 2 and overall I liked. I have played it multiple times, along with all the expansions that I also played multiple times.

Clunky Gameplay? Don't expect that to change with modules. I like the way it plays.

If you want to control a party, then NWN is not the game for you. NWN2 is a party control game.

But NWN is pretty much my favorite all time game, BUT I don't like controlling a party. That is more like a tactical combat sim. I just want to play my character.

So pretty much only story can change.

If you want to try something different story wise from the community. My favorite module with a Story that grabbed me was:

The Prophet series:
https://neverwintervault.org/project/nwn1/module/prophet-prologue-it-cannot-be-denied
https://neverwintervault.org/project/nwn1/module/prophet-chapter-i-will-kings-and-mortals
https://neverwintervault.org/project/nwn1/module/prophet-chapter-ii-century-sorrow
https://neverwintervault.org/project/nwn1/module/prophet-chapter-iii-which-destined

The original campaign is a bit on the dull side, it's true. To be honest, I feel like the first chapter is the worst and it becomes a bit better later on, but it might not be worth your time anyway.

Shadows of Undertide, the first expansion pack, is, I think, better, but still nothing to write home about. Hordes of the Underdark, the second expansion, is the sequel to SoU and is actually very very nice.

NWN is not known for its official campaigns, though, but for community-made modules and campaigns. I'd say you drop the above-mentioned campaigns for now (you can come back to them later) and start with some gems (all of which you can download on Neverwinter Vault). Here are my suggestions:

-Darkness over Daggerford - it has a very strong Baldur's Gate feel to it and is generally very well done, so I'd suggest you try it if you say you were expecting too much of BG. It's won a prize for the best RPG mod of 2007 or 2006 if I recall correctly. It's not as long as a fully-fledged game, but not much shorter, really, 25-30 hours, I'd say.

-Prophet campaign - it's not set in Forgotten Realms and it's pretty linear (not many optional quests and stuff), but the atmosphere and the story is absolutely something you can't miss. It's one of my favorite story-based RPGs, if not THE favorite one. A good-aligned character is recommended, for the story makes the most sense in this case. It's easily 40-hour long.

Edit:
Hah, looks like PeterScott made some of the same points as me, namely recommending the Prophet series and acknowledging the original campaign gets better later on. ;)

Anyway, once again, I'd say you start with the best NWN has to offer, which is custom content. Once you feel comfortable with the game and realize how good it can be, then you can try out the official campaigns. I think it would be unfair to start with them and put the game aside based on the experience you get with them, because NWN can be so much better than that.

Just echoing what others have said. The OC is the weakest of the three official campaigns, the first chapter is the weakest chapter of the campaign, and the the first half of the first chapter is the weakest part of the chapter. SoU and HotU are significantly better...but it's the custom content that makes NWN truly shine.

https://neverwintervault.org/project/nwn1/module/ultima-iv-reborn-0 is one of the older modules that had a BG "feel" to me with a large party and consequences depending on what sort of creatures your party attacks and kills. I remember in the original Devi there was some transition problems transporting all members of a large party but nothing gamebreaking. It was fun to experience Ultima using AD&D rules. I believe it still requires only vanilla resources to play it.

Check the legacy Hall of Fame and read the description to find modules and module series that suit your fancy. The OC was really only intended to be a learning campaign for new players to become oriented to NWN's version of AD&D 3.0. I find the story and theme of the OC fairly good considering the RPGs that were roaming the horizon in 2002 so bear in mind the era you are attempting to evaluate 15 years later. SoU is by far Bioware's best PnP-like creation, low-magic, resource-intensive focused on ability micromanagement and interlacing of storylines. HotU departs into the opposite direction, high-magic, resource-flushed with little dependance on toon development (just about anything works with all the uber gear available).

But NWN still shines on-line, especially with DM'd server play. It's like night and day when you move onto server- or LAN-based gameplay so get some practice playing around with single-player until you are ready for some interesting and innovative worlds without a Pause button or Save/reload game crutch.

I like enjoy the original game, takes awhile to get into it and the prison section is very tough.
But unlike others i don't have a problem with the story, it's gets a bit silly as you go on with lizard men and stuff but i highly enjoyed chapter one and two, it's three that becomes a bit of a bore and repetitive quests.

Both expansions are more of the same, they don't tend to add too much content to the original from what i can tell.

You might be better off with something like the new-ish Gauntlet which is nothing like the original which you may remember but that's a dungeon crawler with a mass party.

The first chapter of NWN ( the four districts) is kinda boring with a lot of repetitive combat. Part of the reason is they used it as kinda an extended tutorial, it is mostly melee enemies with no real AI other than charging at you. There is also a design flaw with the crates/barrels where there are just too many of them, which take awhile to open and slows things down. It does get much better once you finish the four city districts.

But for what it is worth, the first expansion starts over again at lvl 1. So in reality you can play either the original game, or the first expansion before moving into the second expansion.

Or what I usually do is go back and forth. I will play the first chapter of the original, then play the first chapter of the first expansion, then the second chapter of the original, then the second chapter of the first expansion. This will get you to be a little overpowered so you can play non-optimal but fun builds and also speed through the repetitive combat. It will also start you a few levels ahead of where you should be for the final expansion, which again makes the boring fights faster and allows for fun builds.