The same could happen in reverse though, not everything is light years I front of us, there is many plannets and stars that are light years behind, just because we can't see them yet doesn't mean they're not there
This is easily possible in either direction, there could be thousands of solar systems out there just like ours at totally different stages in evolution, some could be hundreds of years ahead or behind, some could still be at the dinosaur period and some could be mear weeks away from our current progress in evolution
Declare war without their knowledge, nuke em, flush them out of their petty homes, eliminate resistance, enslave them, take all their resources, live the life of kings.
What a waste.