Earth-like Planets

Recently, there have been discoveries about Earth like planets in our galaxy, from what I've noticed; scientists tend to find things like air and water on these planets, and while it's interesting to think about humans inhabiting another planet it's also scary to think of what could also be on that blue planet like ours. One thing I would find interesting is what is on these planets, like what plants and animals are on it and how we could use them to our survival and advantage. Another thing I sometimes think about is how many light years it would take and how long it would take for humans to adapt on these planets. One thing that has come to mind is this: what if humans aren't capable of living on other planets? How would we try to save our own if that was the case? While these thoughts linger through my mind, it's still a cool concept regardless.