Sim can't form relationships at all despite interactions

@MinajSimmerr   Ugh!  It's terrible that the intro issue isn't fixed after all that.  One friend did suggest that the sim could be corrupted somehow.  Perhaps you could try saving the household to your library and then loading them in a mod-free save.  When you save the household, they will keep all their money, skills, and levels when added to a new game but they won't keep inventory items or relationships outside of the household.  It might be a good way to test if your save or your sim might be corrupted somehow, if your celebrity has the intro options in the new save.  Before creating the new save, make sure all mods and mod-related folders are moved out of The Sims 4 folders. Also, you probably want to delete the localthumbcache file again.

As for those sims you mentioned ... there are certain features of that mod, when enabled, that create NPC sims to fill specific roles or may assign roles to existing sims.  When the mod is removed, those roles no longer exist.  I have no idea why they all show up at my sims' door like that though.  However, it's possible that the game doesn't know what to do with these unfulfilled sims since their roles were removed, so they just spawn at your lot when loaded.  I don't think it should have any impact on your game though.  When it happens for me, they usually leave the lot fairly quickly.  And, if you do create a new mod-free save, those roles (and rando NPCs) will never have existed.

Dang I was hoping I wouldn't have to make a new save ): But I appreciate your help so much!!! If you know, how does a sim become corrupted? Is there anyway I can avoid it next time? 

@MinajSimmerr   Unfortunately, I don't know specifically what might cause sims or saves to become corrupted.  I think there could be a number of factors from unsupported mods/CC to conflicting mods to some random glitch in the code.  One glitch that causes a last exception might be enough to corrupt something; some piece of code that failed for one reason or another.  The only thing I can suggest to prepare for the potential is to make sure your game and mods are updated regularly.  A lot of people turn off game updates until their mods are updated for each patch but eventually they should all be synched.  Another preventive measure would be to regularly make backups of your saves so that if you do see a problem that you're not able to fix, you could try reverting to a backup before the problem started.  The game does have a built in restore feature but that may not be sufficient, depending on the problems you're having.

Speaking of last exceptions, have you noticed any LE's popping up since you noticed the issue of not having the intro options?  Sorry I didn't think to ask about that before now.

I tend to ignore my LE as long as I can play so I couldn't even tell you LMAO ): I'm definitely gonna take your tips into consideration & take care of my game better. I've been getting this error code for a while, i tried to look it up but it didn't really effect gameplay

@MinajSimmerr    I tend to ignore the LEs also, as long as I'm not experiencing anything funky, so I don't blame you for that.  When you're experiencing issues, though, they can give clues about the cause. 

I researched that error you shared and I see a number of articles that indicate it is probably caused by broken / outdated mods.  Here is one such article from AHQ Hero crinrict...
https://sims4.crinrict.com/eng/crin-error/error-code-140645fba83/

I can't say for sure that this is what caused the no intro options that you're seeing but it's possible something from a mod did corrupt your sim.  If you want to keep playing with mods (which I'm sure you do since I wouldn't enjoy the game without mine) then you definitely want to make sure they're all updated and compatible with the current version of the game.

Out of curiosity, did you try loading your celebrity in a new save?  If so, did you experience the same issue or did you get intro options?

I just tried it and even in a new save he doesn't know his son & still can't intro. And I am pretty sure I have that baby shower mod & its outdated that will hopefully fix that error code

@MinajSimmerr   Double ugh!  Would you mind uploading that household to the gallery?  I'd like to download and test to see if it happens in my game.  If you do upload them, maybe name it something like "Friendless Celebrity" or something to make it easy to find, then let me know.

In the meantime, I wonder if you could try having the celebrity quit the spotlight in the test save.  Just to see if the intros go back to normal.  Then enter the spotlight again and see what happens.  I know it would suck to have to start over the fame development from scratch but I don't know what else to try and you might have to start over anyway. :-(

Also, have you tried playing another celebrity to see if they have intros? Maybe try Judity Ward.  She's a 5-start with some perks and quirks already. 

No problem I just uploaded him! And i'll try leaving the spotlight now & see if that fixes it. & his wife is also a celebrity & can do all intros

In a new save now, I quit the spotlight & still no. I'm thinking I'm just gonna have to kill him off lmao

@MinajSimmerr     I'd hate for you to have to delete him but I'm running out of ideas. 

I looked for the household in your gallery catalogue but I'm not sure which one is the problem household.  The last one I see is Alexandra Louis shared on the 17th.  Do you have another account User ID that you used?