>>80308
They wouldn't need to bother with Earth at all aside from pure scientific curiosity. If they have the level of technology capable of allowing them to travel the stars within a lifetime (or several lifetimes) - then nothing Earth has to offer them can't already be found or synthesized far more easily elsewhere in the universe. Life, and intelligence, are almost certainly not unique to Earth either. The only thing it has that's truly unique to Earth - is our own particular evolutionary history. If they're even interested in that - tinkering with it would introduce impurities and ruin the sample.
Are we alone? Do Aliens exist? The answer to both is probably yes. All indications from other fields of science suggest that the environments and materials that made us are extremely common in the universe. But the entirety of the Human species is barely a flash in the pan in terms of the vast timescales that the universe operates at. And in 3.8 billion years of life, we're the first species that we know of that has attained our level of intelligence. The most likely scenario that I see is that the universe is absolutely teeming with life, including intelligent life, but the distances that are between them in both time and space make us functionally alone.
All we're probably going to find out there are a few savage planets and long-dead ruins. The first aliens to make contact with humans, will probably be with our skeletons.