Internet Person

Check the latch/locking tab for the pcie slot.

Something must bent, as others pointed out. My guess is that the rear metal bracket (that part that goes into the rear of the case) isn't going in all the way. Either because the case or the bracket itself is bent.
 
And yeah, for Pete's sake, clean it!
 

Need more information and pictures.

With that monitor that you have it's hard to go with anything below a 1080Ti as it requires quite a capable GPU. You'd at least be able to run some games at medium settings and decent fps at the G9s resolution. I would not recommend spending money for a new 2080 Super as it will have terrible resale value once the 3070 and 3060 become widely available.

Buying any capable GPU at this point seems like a waste of money. The new cards are hard to get indeed and probably won't be easy to get for few more  months. It's worst launch ever, but eventually you'll be able to get one. You just happened to build a new PC during this frustrating time. If you must get something to keep you going meantime, the only sensible solution seems to get something used.

also give it a clean

That's a good budget kit. Micron E-die afaik. I recommended it recently, and also frequently recommend to 2x8GB kit of it.
This kit should be able to OC quite well. Memory overclocking can be a huge pain, but some people (me included) are masochistic enough to enjoy it. Here is a place to start in case you are interested:
 
 

No, I don't remember seeing that. I built a PC during my Christmas break last year. I got the best deals later in December. Micro Center in particular. They had mobo+CPU combos on top of already discounted 9900K.