I have not watched all the Avengers stuff, I haven't been a big superhero fan from any of the universes. I never had comics as a kid, I was the weird kid that read the entire Funk & Wagnall's encyclopedia. It would take me 1/2 an hour to look up a word in the dictionary because I kept reading all the other interesting definitions along the way.
That being said... I think "WandaVision" is really well done. I like the concept and the execution. I have to admit, I had absolutely no concept of who these characters were. I had to look them up on the internet to get the background story.
I have only seen the first Avengers movie once, and a couple of the Thor movies. Now, I think I will go back and watch "Endgame" and "Ultron". Are there others that I will need to watch to get the whole context?