> I'm new to the codebase and I just want to know how it (the codebase) works.
You should want to know _why_ it works that way too if you want to do any meaningful work with it. Context matters. I’ve seen many cases where the way something works seems dumb, only to learn later they had already tried the “smart” way but ran into some obscure problem which the “dumb” way solves.
This is important. As soon as we come to the understanding that the coders that came before were not all idiots then we are forced to ask the "why". There is generally a decent reason why something is coded the way it is. Could be as simple as it was an emergency and meant to go back and fix it but never had the time or it could be a valid business edge case that absolutely had to be wedged in. There is almost always a why. Otherwise you tell everyone about a fix you made that 3x performance and you see their faces go gray as they explain you just shut down some archaic but mandatory process in Singapore.
You should want to know _why_ it works that way too if you want to do any meaningful work with it. Context matters. I’ve seen many cases where the way something works seems dumb, only to learn later they had already tried the “smart” way but ran into some obscure problem which the “dumb” way solves.