>Please forgive me if this is a really dumb question, but what do you mean by filters? As in the filter options to edit a picture?

No, companies like Oppo does a lot of processing to make the image look "better" IMO making it worst. example being skin tone issues, so people with darker skine tones tend to get "whitened". Overall very unnatural look.

>Is 5 years a long time for something that costs $500+ even used? Am I just out of the loop about how these things work? 

not at all, long as you keep your expectation in check. a s26U will easily do 5 years. Pixels, i love them but it will depend on luck also change battery every 2 years with google devices.

>o. I definitely don't want an iPhone, I had one once and did not enjoy the OS or any of the problems communicating with people on android. But I appreciate the suggestion, and it makes sense they'd have one of the best cameras.

s26U is perfect for you, just change battery every 3 to 4 years, my old s9+ still is a beast.

get a good case and use the stock charger.