Hypothesis: adding this part or doing that thing will make it do what I want.

Experiment: do that change and see if it does the thing you want.

If it doesn't do what you want, go back to hypothesis step. If that's not science, idk what is.

Just because the theoretical was finalized after the practical, doesn't mean that it isn't applied science.

We made wheels. We didn't know why it made sense for them to be circular, but we knew it was easier to load them.

Later on, we learnt about catenary tracks and how circular wheels are great for reducing friction by reducing the contact surface area, as well as the fact that rolling is easier compared to pushing or pulling.

All of these are things that we instinctually understood but didn't know how to explain.

This was, is and will be how science works. You see something happen, and you try to understand the how and why.

All of theoretical science comes from experimentation, which means on some level, you will require engineering. Similarly, all of engineering comes from the gradual process of perfecting how things works (or can work), which is science.