What is going on with this game? Confused new player

Follow up question, are there any realism settings or mods that makes the game immersive

First off your post was hilarious! Thanks for the laugh.

The game is a god awful mess especially the base game and many players like myself mod out all the games annoyances. However the modding scene is a steep slippery slope and mods, will break with every update so get use to refusing updates until you see fit. If that hasn't scared you off heres  a few things to look into:

To make a lot of mods work you need: https://scumbumbomods.com/xml-injector

The two best places to find mods that i know of is:
CurseForge: https://www.curseforge.com/sims4/search?page=1&pageSize=20&sortBy=relevancy
Scarletrealm's mod list: https://scarletsrealm.com/the-mod-list-sfw-only-edition/

Some of my go to Creators for fixing the game (just google them):
LittleMissSam
TwistedMexi - Mostly for "better build buy" and their cheat extensions to make building less anoying
Bienchen
Kuttoe
Zero

Short list of mods for realistic gameplay:
MC Command Center - A boat load of utility's from changing lifespans, slowing skill gains, relationships and to preventing sims from doing certain actions - A Must Have!
Wonderful Whims
Carl’s Gameplay Overhaul
Give Sims Some Talent
Have Some Personality Please   - Also get the restricted Romance module for those romance problems your having!    
Meaningful Stories
Better Exceptions   - Helps find broken mods and keeps your mod folder healthy!

This should serve as a good starting point the rest is in your hands to find and explore mods to better suit your tastes.

I also recommend trying to stay clear of any cosmetic mods if you can resist it. They can turn into a pure nightmare fast, also takes up a lot of space in your mods folder.

If that seams all to much for you there is a Life Sim game on the horizon that looks promising. It focuses on realism and quite frankly looks stunning and that would be "Inzoi" - Check it out!

Sounds like you got that ancient curse, "May you live in interesting times." 

Go to Gameplay options and you'll see Allow Romantic Invites and Requests. Turning that off should stop NPCs from proposing. If you leave it on, proposals are pretty common after successful dates if both Sims are single. The proposals can get annoying, especially if you're playing the Serial Romantic aspiration.  

I've never had a Sim drop dead from rejecting a proposal but I suppose it could happen. The Sims 4 has some emotions that can cause death and Embarassment is one of them.  

Try For Baby unlocks at the same relationship level as Woohoo. It doesn't cause adoption but it might cause pregnancy, so you may get another phone call in a few days to let you know a child was born.

The adoption message was just a coincidence, I'm sure. Adopted Sims can range in age from Newborn to Child, so the adopted Sim might have been a Child and off at school or somewhere else. You can stop adoptions by turning off Neighborhood Stories under Gameplay options. You might need to scroll down to find the option. You can also stop adoptions by changing the Neighborhood Stories settings in Manage Worlds/Manage Households. 

I don't think you need mods, although there's nothing wrong with using them. I've been playing TS4 since it was released, over 10 years ago, and I've never had any mods. Based on what I've seen in the various forums, I experience a lot fewer bugs than the players who do use mods. 

This is why I love the Sims. So Unhinged. 

Thanks for the replies! I'm not really playing for any specific aspiration or challenge, I just want it to feel just a tiny bit realistic as I otherwise find it difficult to immerse myself into my character. I'll try the gameplay option for now and look into mods if I find it necessary :)