If you were shrunk down to the size of an atom, the concept of "distance" would become quite different from what we normally perceive. At such a tiny scale, the rules of quantum mechanics would govern your behavior, and classical notions of distance would no longer apply.
In quantum mechanics, particles can exhibit wave-like properties and exist in multiple states simultaneously. They can also undergo a phenomenon known as quantum tunneling, where there's a small probability of "jumping" across barriers that would be insurmountable in classical physics.
Given these considerations, if you were shrunk down to the size of an atom and wanted to reach another galaxy, you wouldn't have to physically traverse the vast distances between galaxies. Instead, you could potentially exploit quantum phenomena to "tunnel" or exist in multiple states simultaneously, effectively bypassing the traditional constraints of distance.
It's important to note, though, that the concept of a human being shrinking down to atomic size and traversing intergalactic distances is purely speculative and currently beyond our scientific understanding. Our current knowledge of physics does not provide a concrete explanation or mechanism for such an occurrence.