Is God the Creator of every atom in my body? Are these questions whispers [from Shaytan]? Is ignoring them an act of disbelief?

Allah is the Creator of all parts of the human being, as indicated by the noble verses such as: "And Allah created you from dust, then from a sperm-drop; then He made you pairs..." (Fatir:11), and "It is He who created you from dust, then from a sperm-drop, then from a clinging clot..." (Ghafir:67), and "Did We not create you from a despised water?" (Al-Mursalat:20), and "Allah is the Creator of all things" (Az-Zumar:62), and "Indeed, all things We created with a [decreed] measure" (Al-Qamar:49). As for intrusive thoughts (waswas), their cure is to completely disregard them and occupy oneself with what is beneficial.