That's more to do with their original role having extremely high mortality rates. "Honoured Elder" titles for those who live to 20 were exceedingly rare. DS9 only really mentioned them once when Dax spoke with a Jemhadar during the Iconian Gate mission, then later in the episode the runabout shrinks one of the invading Jemhadar was an Honoured Elder but still only Third or something. Without a life purely focused around combat the lifespan may end up far higher than expected.
It's still going to be done extremely poorly in this show, however.
This show is going to be such a literal shitshow.
There's a female Jem'Hadar.
A race previously not only entirely male, but one that reproduces through cloning and as such DIDN'T NEED FEMALES IN THE FIRST PLACE!
A race that lives for 10 to 15 years, and she's been teaching for 25 years.
That's more to do with their original role having extremely high mortality rates. "Honoured Elder" titles for those who live to 20 were exceedingly rare. DS9 only really mentioned them once when Dax spoke with a Jemhadar during the Iconian Gate mission, then later in the episode the runabout shrinks one of the invading Jemhadar was an Honoured Elder but still only Third or something. Without a life purely focused around combat the lifespan may end up far higher than expected.
It's still going to be done extremely poorly in this show, however.