so people living in average like a few millions of years.

"Curing aging" isn't enough on its own to get a million year lifespan; an 18-year old male in the United States has about a 1 in 1000 chance of dying before reaching his 19th birthday*, which would imply an average lifespan of about 1,000 years.Of course, by the time we do cure aging, we'll probably have solved a lot of other problems, too...