Before I start I want to say that Humankind looks amazing. I love it. A lot of the little features like sheep running from the cursor and the variety of biomes really bring it to life. This criticism comes not because I think that the game isn't good enough, but because I love Amplitude's work and I think it could be even better.

Everything looks dry. The whole game. All of the dirt looks like red clay and all of the trees look like they are in a drought. Even the beaches look like clay, not sand. One might think the game was named Civilization: Yellow. I understand that many parts of the world dry out in summer, but why make a game take place in summer when it could take place in spring? Why not show the landscape at it's best? Here are two screenshots which I have crudely altered the color balance of to show my point:

The upper right is my change, lower left is as is. Original here. I made the grass area greener, the field on the right golder, the water bluer, the sand more pale and yellow, the trees less yellow and more green, the city dirt more pale and less red, and the grass greener there too.
The two boxed in areas I modified. Original here. I made the water more cyan, the beach more pale and yellow, the grassland less orange and more green, the trees more vibrantly green, and tuned down the yellow in a few odd places.

Even the water looks dry! Below on the left is the average shade of water in game, the right is a shade from my modified portion of the image.

The shade on the left I'm not sure I would even describe as "Blue". "Blue-Brown" Maybe? The Great Blue-Brown Hole.

I don't think any of the actual textures or models themselves have any issues. I think each part of the picture looks great, I really do. Each tree, mountain, building, and river looks good on it's own. I'm really looking forward to playing this game, more than any I have in a long time. But I encourage the devs to take a step back and reconsider how the palette as a whole balances out.

Yeah I'm kinda with the OP here. Most areas look like they could fit south of Sahara or Australia or something. Those tilesets don't bring Sri Lanka or Scotland to mind.

That said, it doesn't really look bad. I'm with the OP there as well. Individually everything looks really nice and I like the overall tone and feel too. Artistic direction and all that.

And I'll agree with the notion of rethinking how the big picture looks too. Is the palette what you really want from the game? It looks good alright, but could it be improved?

Personally I'd probably keep everything that there is (because they look good!) and just add a few more landscape sets for the more fertile/tropical areas of the world. Maybe that's already in the works, with the game being in alpha and all.