You're telling me what you've learned is that no insight is possible, all we have is dumb experimentation?

See, this is exactly why I tried asking someone at first, I wanted to get some knowledge from someone who knew. But I couldn't find such a person.
OFFER STILL STANDING!!!
Swimming. How often? How intensive? Should I wear myself out as much as possible every time or not? Should I swim the same every time or alternate something?
Yes, exactly. If you've decided to get of your ass and do some exercise, after God knows how long, fact is any volume and method will do you good. After a few months, your body will tell you when and how to step it up. IMO in swimming, your first step should be endurance, so just swim as often as you can. When you get endurance, mix up styles, 2 laps one style, 2 laps other, etc. You're not going for the olympics, just swim dude.
I was like that in my first couple of months in the gym. Always researching, asking what is the best way, how often this or that, etc. When the bottom line is, no matter how good the routine is, you're a beginner and you're not gonna get some amazing results instantly. It takes a lot of time and effort. After a while you get stronger and you see how your body reacts to what exercise and stuff like that, so you know yourself how and what to do. Swimming is different, but it's even less of a science. Swim freestyle, then when you can pull a number of laps easy-peasy, try any other style and mix it up. Don't burden yourself with what other people tell you, I lost 2,3 months of gym time because of that. No one knows better than yourself. Unless you wanna go pro.