That's where you have to actually study it to get the understanding. With calculus you use an oddly specific set of rules to manipulate equations either going in one direction and simplifying them or going in the other direction and making them annoyingly complex. Study that on its own and it seems entirely pointless but start applying those processes to questions such as "how fast do I have to throw this ball to hit that car over there" and things start getting interesting in that all the details can be found from taking the simple base equation and expanding it with calculus and suddenly you not only know how fast you have to throw but at what angle to compensate for gravity so it hits at the right height and so on. Once you wrap your head around that and move on to find out that the same set of rules applies to everything from water moving through a pipe or electricity and so on. Pretty much everything that does a thing is governed by calculus and it's obviously intelligent design.