If aliens cultured our species as an experiment, were they responsible for smallpox killing natives in the new world?

I’m assuming that humans were cultured and perhaps genetically designed by aliens and nudged along in a certain direction over the millennia. In that case, when the Spanish set foot on American soil, did those higher powers decide to kill off the native culture using smallpox for the more “favorable” European culture to their experiments?

Wild speculation of course. What are your thoughts?