If you want to stick to LWJGL, your focus should not be to make a game, but instead to learn how graphics programming works. Things like shaders, matrix math, meshes, etc. If you want to learn game programming like physics, collision, tiled maps, etc. you should use a library that handles all the boilerplate for you, like LibGDX.
I don't think I've seen this written quite as definitively before, there is usually lengthy discussions and debating making it difficult, for a newbie, to see where the focus is in each API. As a result, I decided months ago to pick up LWJGL and slick for making 2D games (I saw libgdx as the API for android...), even though I've barely touched anything in LWJGL to date! I'm now thinking that I should be making the switch to libgdx, as I could be saving myself a lot of time.