Jurassic Park is a fun movie, but a terrible idea. Cloning a wooly mammoth falls into the same category. These animals are extinct for a reason. Humans might have wiped out the passenger pigeon, but maybe Nature wanted the skies cleansed of the immense herds of these poop machines. Imagine the ecological damage a thousands-strong flock of birds could do. Perhaps the mammoth was so terrifying that it was a good thing our ancestors killed them off?
One of the great unintended consequences was the absolute destruction wrought upon the indigenous peoples of the Americas by European diseases. It never occurred to the best scientists of the time that could happen. You may argue that we are much advanced scientifically in the modern times, but it was not so long ago the best scientists thought you treated a cut by smearing it with horse dung or that bleeding cured just about anything. Is there reason to believe future scientific minds will not look back on our own era and marvel at how crude, how inept, how wrong we are today?
Nope. They’re going to sneer at us the way we sneer at those medieval types, and for exactly the same reasons.