You have a "Hollywood" view of alchemy. Most of the people who did it did not realistically expect to succeed. But they continued anyway.
History is full of people who did all sorts of experiments to try to understand how the world works.
It is not necessary to have a goal "understand this" in order to do science, it's enough to have a goal "what happens if I do this". If I do an experiment and find an interesting result, and I publish it, that's still science - even if I have no idea why what I did works.
I'll ignore your undignified cheap shot. Without understanding this as a conscious goal then a directed systematic inquiry that becomes highly integrated into culture and the economic system will not develop. Inventing the printing press, for example, without a sufficiently rich ecosystem in which it can nurture and grow prevented any catalytic effects that might have otherwise formed.
History is full of people who did all sorts of experiments to try to understand how the world works.
It is not necessary to have a goal "understand this" in order to do science, it's enough to have a goal "what happens if I do this". If I do an experiment and find an interesting result, and I publish it, that's still science - even if I have no idea why what I did works.