The story in question, At the Mountains of Madness, isn't about any of those things. It's about an Antarctic expedition that finds the ruins of an ancient civil

The story in question, At the Mountains of Madness, isn't about any of those things. It's about an Antarctic expedition that finds the ruins of an ancient civilization, which they gradually realize wasn't built by humans. I do think you're right that Lovecraft's ability to write effective horror was largely because he himself was fascinated with terror at the world. But I don't think his weird xenophobia is what he ended up actually communicating to most readers or what he's famous for. He's more known for misshapen tentacle monsters and cosmic-scale horror. For example, Lauren Beukes' novel Broken Monsters is often considered Lovecraftian horror, and it has fairly modern sensibilities.