Stock rom without root was pretty decent for me. No ads at all. However, I only use free software apps mostly from F-Droid (and uBlock Origin takes care of the web). I knew that this was putting myself in a bubble, but I had not realized that the experience of using a phone for a lot of people must be that annoying. What a shame. Computers should serve humans, not the other way round!

I discovered Google Play's App Store on someone else's phone, that was painful and stressful. But what you are describing seems hellish.