I don't feel we should be surprised at all that similar brains processing similar information will arrive at similar conclusions.
In any sufficiently complicated system emergent properties almost always arise. At every scale things are more than the sum of their parts. Atoms are not just quantitatively greater than the neutrons, protons and electrons of which they are made -but they're also qualitatively greater. That is to say, atoms have properties that its parts don't.
As we scale up complex molecules have properties that the atoms of which they are composed simply don't - like metallic, ionic, and covalent bonds. Chains of these molecules - like RNA and DNA - also have emergent properties - like self replication. Put enough of these self replicating molecules together and suddenly you have something even greater - like cell. Put a whole bunch of cells together and you end up with something even greater - like an animal. Put enough of these animals together - like humans - and you get something even greater - like societies and cultures.
And trends in culture shouldn't surprise us. To the contrary - they are to be expected. No telepathy required.