Some questions regarding density

[ada]

Hey there Mikipedio, welcome.

You quite on point with your assumptions.

From what I understand, first density is associated with inorganic matter, second density with organic matter that lacks sentience and third density is organic matter with sentience.

I'm not sure what organic matter means exactly, but second density could be anything from trees to animals or early humans. So they too should have some form of sentience.

If first density is all inorganic matter, we are surrounded by it right? The roads, the seas, the rocks and mountains. Are they all supposed to ascend to a higher density? If so I'd expect every planet to "disappear" eventually from our perceived reality. I don't know if this makes sense.

I think you're right, everything around us in a way is alive and full of the creator. It is confusing to think about really, what does it mean that Earth is already vibrating in forth density? It sounds like a paradox that it is both locked in organic first density matter and yet a co-creator of it's own that is already ascended.

And harvesting from third to fourth? Are humans supposed to go extinct once the third and last harvest is over? As this planet would enter fourth density and be inhabited by fourth densities beings. (only them?)

It's not about humans only, there are many beings from all around creation that dwell here and inhibit the human body. The planet will cease being beneficial for the lower density life and support forth density, in some point in forth density where it becomes fit fifth and sixth density beings can join them.
So in a way, even though we are in third density, we are surrounded by beings from almost all densities.