Im an undergraduate in math, I do extremely well, but I feel like I don't understand anything.

So I just finished my linear algebra course, and I did extremely well in it. I also did extremely well in diff eq and calc 1 - 3, but the thing is I have no idea what I'm learning about. Like I understand how to find a determinant, eigenvalue, how to do a laplace transform, how to do variation of parameters, all of that fun stuff, but I don't understand the motivation and how it was derived. I guess I don't understand why the laplace transform works and what it does exactly. What is the purpose of having f(t)e^-st? Why are we integrating that? What does the determinant show us? Why is it significant? Why are eigenvalues important? Why does matrix multiplication work the way it does? The list of questions I have goes on and on, but these are the kind of questions I struggle with, but I can solve the questions on my homework/tests just fine. is this a normal thing to struggle with in the younger years of studying math? I want to major in it but as of right now I feel like I'm just "doing" problems rather than understanding the meaning behind the equations, and how they were found/discovered, and the motivations behind trying to find these equations. I've aced every math class I've been in up to this point, but I just don't feel like my knowledge of math is that high.

An example of what I consider my lack of understanding on concepts I feel I should grasp is that I read a betterexplained article last night about i, and it totally blew my mind. I never realized what i truly was, just a 90* rotation (something like the 2nd dimension of numbers? I'm still not exactly sure but I get it way more now), but I've been using it for like what, 5-6 years by this point? It just feels like sometimes I don't truly understand the math, just the computations.