@clarissa_ Honestly this post really resonates with me and my own recent experience. I'm 32 and in the past six months I've advanced more with my lifting than I have in the past 5-6 years.
For me it really comes down to your first point, dedication to a lifting program. I strictly do to strength training, as for me 3 days a week is easier to balance around a busy work-life schedule, compared to most bodybuilding routines, such as PPL.
My go to was stronglifts, which I have done in the past, although my progression would stall due to injury, not eating enough, going out at the weekends and not picking it back up for a few days, basically a perfect storm that contributed to a combined lack of gains.
This time around I have experienced so much linear progression that I'm now lifting heavier than I ever have. I stuck to SL until I plateaued, when 5x5 became too intensive and not realistic at the heavier loads. Now I've swapped to a more intermediate program and I couldn't be happier as I continue to see the progress.
Lots of the points you have raised are factors that have played a part in my own success. The major one being getting enough calories. Without a doubt one of the most important aspects, otherwise there's no way I would have achieved so much progress. In the past I always felt like I was eating enough, when in reality it was far from it. I'm a naturally skinny guy with a fast metabolism. In the past it felt like a losing battle until I eventually found out how to get in the extra calories in a 'manageable' way. For me this came in the form of shakes & making sure I wasn't too busy and missed meals.
I also like your point about not ego lifting. For me I just stick to the weight in my program. The last time I decided to go for a new squat PR it set me back a few days, not that I'm saying trying out a PR is a bad idea, however in time you are likely to achieve it by sticking to the progress.