All of this!! I'd also add that the flour and even water quality and type can play a part, plus the whim of the yeast who can sometimes be vindictive as well as generous.
However, as I have said many times to many people, bread is the simplest thing in the world to make - people have been making it for millennia - all it needs at its most basic is flour and water. For a typical white loaf you need flour, water, yeast and a pinch of salt. The ratio of flour to water is important in order to get a dough you can handle and here is where the flour can make a difference and different flours - even different batches of the same flour - can absorb water differently. Having started as a basic baker and simply following a recipe I am now embroiled in the world of % hydration levels, but this is not required learning. As
@Reynard said, watch the dough and do-learn-do. For a decent crust, put a shallow tray at the bottom of the oven whilst it is pre-heating then when you put the loaf in to bake pour boiling water into the tray and close the door. The steam raises humidity in the oven causing sugars in the dough to migrate to the surface and dissolve, which then caramelise to form the crust.
When I tell people I bake bread a common response is "I don't have a bread maker" to which I respond "all you need is a mixing bowl, some hands and an oven".
