Hi! So I just started with libgdx and Im wondering if I should learn how to use Scene2D or use “regular” java, which I already know some, just with using spritebatches and the cool libgdx stuff? 
I don’t see why not, there’s nothing in Scene2d that’s “irregular java”. Whether or not you want to actually use Scene2d, you should at least learn it so you can make an informed choice.
You can compare them first. Try it and choose which one suits you more.