You are assuming that the tech we use now is the only means of travel the stars - I refer you to “James Clerk Maxwell: The man who changed everything”
Four of his 200 field equations were transformed into vector equations by a self taught man named Oliver Heaviside who lived in his mom’s basement.
Those 4 gave us everything we know about the electromagnetic spectrum, and without which, neither Tesla nor Einstein would have been more than obscure family names.
Maxwell postulated instantaneous travel from anyone point to any other point in the Universe as well as free energy (what Tesla was attempting), and more. No one publicly has looked at his original (now rare) work since.
So do not be so certain about what human science knows - chances are that most of what we know is wrong, and the little we do know is distorted.
Of that there is no doubt. That said, what would attract these greatly advanced civilizations to our primitive galaxy? Just askin.