While I see where you're coming from, focusing solely on our bodies might be selling the bike's role a bit short. Sure, our muscles and technique matter, but the bike's geometry, weight distribution, and component selection also significantly impact the ride quality. A change in any of these factors can drastically alter the feel of a bike.
For instance, I once switched from a compact to a standard crankset, and it felt like I was on a completely different machine. The gear ratios changed, and I had to adapt my pedaling style. It wasn't my body that had changed; it was the bike.
Moreover, let's not forget about the placebo effect. If we expect a certain outcome from a change, our perception can be influenced, making us feel like we're riding a "better" bike. This doesn't mean the difference isn't real, but rather that our minds can play a significant role in how we perceive our rides.
So, while it's essential to consider our own bodies and abilities, let's not neglect the hardware. Both have a crucial part to play in our cycling experience.