Yes, it’s resurrecting a long dead species.............
Well, for some, not so long, like the Passenger Pigeon. That’s only been gone for about a century. But there are definite habitat concerns to take into account for some species. I don’t know where they could put the Woolly Mammoth where it would thrive. I think the Irish Elk would be a better choice, but North America might be a much better place to put it nowadays than in Europe. It’s been gone a while but not insanely long, about 12,000 years give or take. It’s habitat is still around, though not necessarily in its original place.
I think trying to bring back the dire wolf (which they didn’t actually do) was stupid. Why on earth bring back an apex predator without any prey for it to eat? Whereas there are vast swaths of North America where the Irish Elk would thrive today even if it was never here in the past.