Could humans be the first intelligent life in the universe?

Yes — it is scientifically possible that humans are among the first intelligent life forms in the universe. We do not know whether that is true, but there are several reasons scientists take the idea seriously:

• The universe had to evolve first. In its earliest eras, it lacked many of the heavy elements needed for rocky planets and complex chemistry. Those elements were built later inside stars and spread by supernovae.
• Habitability may be relatively rare or early. Even though the universe contains enormous numbers of stars and planets, the timing of when suitable worlds form may mean Earth arose earlier than many others.
• Long-lived red dwarfs may host future life. Since many stars are small, cool red dwarfs that can burn for trillions of years, some models suggest the peak era for life could lie far in the future.
• The Great Filter idea. If the steps from simple life to intelligent, technological life are very difficult, then intelligent civilizations may be uncommon — and possibly we are among the first to get this far.

So the careful answer is: possibly yes, but it is far from established. With only one known example of life, we cannot yet tell whether humans are unusually early, typical, or late in cosmic history.