There are many ways to make bread. If you got a technique that doesn't require preheating, that's fine, it's yet another way to make a particular kind of bread.
I will not say that your bread isn't good. However, if you want great crust and oven spring using dutch oven while baking in a home oven, a preheat is a good idea and it works.
I preheat at max temp, 500F for 1 hour with the empty dutch oven inside. Here's a good recipe that I've used recently, it's beginner friendly and uses common flours (King Authur bread and whole wheat blend)... https://www.theperfectloaf.com/simple-weekday-sourdough-brea...
Have you definitely tried the same recipe (except baking time) both with and without preheating? Maybe I’m not discerning enough, and I freely admit my results aren’t amazingly consistent at the best of times, but I honestly can’t tell the difference in the results.
I will not say that your bread isn't good. However, if you want great crust and oven spring using dutch oven while baking in a home oven, a preheat is a good idea and it works.
I preheat at max temp, 500F for 1 hour with the empty dutch oven inside. Here's a good recipe that I've used recently, it's beginner friendly and uses common flours (King Authur bread and whole wheat blend)... https://www.theperfectloaf.com/simple-weekday-sourdough-brea...