These maps show that, according to your theory, Russia is trying to steal coal and metals, but not natural gas or oil. Interesting.

Can you explain why are they fighting down near the lower Dnipro river where there are no resources?

I keep your theory in a superposition of possibilities, but it's not a strong one in my book.  Russia has MASSIVE mineral resources that are untapped... the limiting factor is people and infrastructure, not underground resources.  There is no logic to getting more resources when they can't harvest all the resources they already have.  OTOH if these resource dots already have infrastructure pulling out resource that would be different but I don't tihnk WaPo used such dots.

I think Russia wants to maintain it's Naval presence at Sevastopol and to never be cut off from it (via Kerch bridge attacks) and so they wanted a "land bridge" all along the north from Rostov-on-Don across and right down E105 to always have access to their critical naval port.  I don't think they want to capture any more of Ukraine but are taking it because it strengthens their negotiating position.

None of this means Ukraine shouldn't be fighting them back. If I were Ukraine I'd be doing everything I could to fight them back. But I'd also prioritize what matters most and understand what matters most to my enemy so that some kind of settlement could be made, and try to move the situation towards a peace.

You also argue that "killing people is a part of self-defense."  Turn that around.  Perhaps (another theory) Russia killed people in Eastern Ukraine for self defense. We have even NY Times articles that the US was installing military right along the Russian border including CIA bases.  I think this possibility is strong.

I wouldn't be wed to just one explanation too tightly, and most things are decided based on multiple reasons.