OpenGL is arguably still better for learning the fundamentals of computer graphics. All you really want early on is a simple vertex and fragment shader up and running so that you can learn how to move a camera around, transform objects, basic lighting and texturing, etc. Vulkan is overkill for that. If you follow the LearnOpenGL tutorials you'll get as far as HDR lighting and shadows. At that point you'll be better equipped to understand an API like Vulkan and probably a lot more successful at porting an engine over to it.