So the longer lifespan makes something more significant?

Turtles and even trees don't have a very significantly longer lifetime than humans. Only certain species of turtles can live about 2 times longer in lifespan, most species turtles live about same lifespan as humans- and as general rule, if humans are caring for animals [turtles or lions] they can have significantly longer lifespans.
In following article, called "Common Turtle Species" most are listed as have lifespans of around 40 years:
http://www.klsnet.com/tspecies.html
And it's commonly stated that some species of turtles can live up to 200 years.
Here's something called The Life Span of Animals:
http://sonic.net/~petdoc/lifespan.htm
Another list referring to parrots:
http://exoticpets.about.com/od/birds/f/birdlifespan.htm

In addition to human care, human have the capable of genetically making animals live longer. For instance in the quest of extending human life [something generally thought more important] I heard it mention that a mouse's lifespan has been doubled- and similar stuff to do with extending lifespan of fruit flies. As this science progress it seems that one likely outcome will that some effort will made to genetically engineer human pets which will have longer lifetimes- just today one buy a dog or cat which doesn't produce an allergic reaction to some humans.
So, at moment humans can make animals have a longer lifespan and in within a relative short life [say 100 years or so] human will probably develop ways of extending human lifetimes and become better at extending the lifetimes of human pets or other animal in which their any human interest in extending their lifetimes.
A turtle or tree within a timeframe of a million year to never will lack the capability of extending not only their lifespans but other species' lifetimes.

And trees though in general have around twice the lifespan of humans, only a few species of trees have the possibility of living more than 1000 year. With space travel human have potential of extending the lifetime of "normal" humans thousands to millions or billions of years in duration- by altering time itself.

So if timespans is important it seems to me that the human species is not insignificant.