Let me preface this by saying I am a man, and smoked a little too much, so I'm sitting here thinking... what is or was the original purpose of a bra? Weight support? Vanity? Covering the nips so people's eyes met your eyes and you can have a normal conversation? Like what's it all about?
I'm actually quite interested in dress history. I'm an engineer at heart and clothing is fundamentally also an engineering problem (and design of course). It's an area of engineering that was always dominated by women and you can sometimes see the novel approaches that brings.
For example historical corsets were actually quite comfortable when fitted right. One reason why is actually breast support. Predecessors to the modern Bra did exist but were not in fashion as a more compressed looking bust and later a shaped silhouette was in fashion.
Also it's cool what tricks one can use to form the silhouette without extremely compressing the waist (which is how many modern people often think is the function of a corset).
I recommend Bernadettes channel on this topic: link