Scientists are getting very close to bringing a few iconic species, like woolly mammoths and dodos, back from extinction. That may not be a good thing.
Not that long gone—the last relict population on Wrangel Island only died out about 4000 years ago. That's (barely) within historic time. There are probably islands in the Canadian and Siberian Arctic that could still support them (and have no or few human inhabitants).
I see two big issues. First of all, not all knowledge among elephants is transmitted genetically, and I expect mammoths were the same. Who will the new ones learn from? They'll have to redevelop best practices for dealing with their environment from scratch.
Secondly, global warming. This seems like about the worst possible time to bring back an ice-age-adapted critter. We'd be better off transferring the effort spent on this project into de-extincting the thylacine, a more recent loss which doesn't have that specific issue.
Different group, I think, and not as close to success. The thylacine has a better chance at long-term survival if we do bring it back, though—it isn't an ice age creature, and it was surviving despite competition from other creatures in a similar niche until humans started aggressively hunting it down.
It's not that long gone. There were still mammoths around when the pyramids were built. Plus there's still huge swaths of tundra and taiga that they could live on, with a lot of the same plants, even if it's quite a bit warmer.
A good measurement for human timescales is the age difference between a child and their grandfather (~50 years, basically one generation of oral tradition).
The mammoths died out 80 grandfathers ago.
Not advocating for restoring the mammoth, but this is a dangerous line of argument.
With climate change and ongoing mass extinctions, many current species are or will soon be in the same situation that re-introduced mammoths would be—and you could use the same argument to say that trying to preserve them is cruel so we should kill off any current species facing environmental stress.
It's worse when you consider the state of the world and the warming. They'd have about 20 sq\km of land capable of supporting them and they'd have to share it with those psychos, polar bears.