It’s Hydrogen that’s existed since the universe cooled enough for electrons and protons to make atoms. Seconds after the big bang.
Atoms didn’t exist until 380,000 years after the big bang. Before that the universe was too dense for atoms to form and everything existed as a hot dense plasma where no electron could be captured by protons and neutrons. The protons that make up the nucleus of hydrogen did exist, it’s just that everything was too energetic to become an atom yet.