You do realize every specific similarity you brought up also applies to Hytale and Vintage story (except for the pumpkin part because in Vintage story they don't grow in the wild). Could it be that there's a completely different reason those similarities exists?
Perhaps grass texture with the side showing dirt just looks visually more appealing than an entirely grassy block? Pretty much every minecraft-like game does this. Even Terraria does the same thing in a 2D space.
As for pumpkins and trees. Pumpkins in the real world also grow in groups. If we consider the fact that the pumpkin has to be a cube there's nothing specific about it growing in the forest in clumps, that's just imitating the real world. Similar thing with trees. Most trees also grow from a single trunk that's sprawls wide at the top. That's just how trees are.
And what even is "minecraft-like" terrain generation? I'm pretty sure Minecraft has gone through at least 3 different variations of world generation. The latest version of Minecraft world gen looks nothing like what is generated in Allumeria, or perhaps it would be more accurate to say the opposite because Minecraft latest world gen is very refined and Allumeria simply doesn't have that level of refinement in its world gen. Allumeria world gen is closer to the alpha/beta version of Minecraft world gen.
What I'm getting at is that the specifics in that single image can be what make it look like it's Minecraft, but there's a reasonable explanation for all of those things and any resemblance ends up coincidental. It looking like Minecraft is just as coincidental as my picture looking like KCD.