Assuming you're not a Stormtrooper, what is the natural lifespan of a human in the Star Wars galaxy?
According to Lucasfilm Exec Leland Chee, the typical lifespan of a human in the Star Wars galaxy is almost exactly the same as that of a human on Earth (e.g. 70ish years).
Q. What is the average life-span of a human in Star Wars canon?
LC: Similar to real-world. Was easier to say they lived longer in Legends because we didn't have to account for actors getting older.
This makes sense because humans in the Star Wars galaxy are "anatomically identical" to Earth humans.
Sources vary, but it's either around 100 years of age according to the Star Wars RPG Core Rulebook
Physical Description: Humans average about 1.8 meters tall. Skin shades run from nearly black to very pale, hair from black to blond. Men are usually taller and heavier than women. Humans achieve maturity about the age of 15 and rarely live beyond 100.
or up to 120 years of age (and over 200 for Force Sensitives and Jedi) according to the The New Essential Guide to Alien Species
Humans can typically live up to a hundred twenty standard years, though there have been isolated reports of human Jedi living as many as two hundred.
Going by JUST Episodes I - VII, we have Obi-Wan Kenobi as one example. Now, granted, Obi-Wan Kenobi lived the first part of his life well-nourished and physically fit as a Jedi Knight, but also put under more extreme situations than the average human being would presumably undergo.
In Episode I, Obi-Wan was 25 years old. Though, the exact wording that they used was "a quarter century" in the Phantom Menace novel, so he's 25 standard galactic years old. Judging from his appearance and the descriptions used, he's about the same as a 25-year-old male in our galaxy a long time later and far, far away.
Episode II takes place ~10 years later, making him ~35 years old
Episode III takes place ~3 years later, making him ~38 years old
Episode IV takes place ~19/20 years later, making him ~58 years old.
This is also the age where he dies by unnatural means.
At that point, people refer to him as "Old Ben" and "old fossil", so he's presumably in his latter years by typical human standards of the galaxy. Now according to this related question, Obi-Wan seemed to age more quickly after the events of Episode III/his life on Tatooine. So he was ~58, but we'll say he appears to be ~60/65 years old.
Humans in our galaxy living in the United States are given a life expectancy of ~78.8 years. At around the 50-year mark is when they're considered 'over the hill' and in their 'golden years' by the time they near 60. In Episode IV, Obi-Wan was considered to be at about a similar level. So it would be a reasonable to conclude that humans (at least, Jedi humans?) in the Star Wars galaxy also have a natural lifespan of ~78.8 years.