If such a thing occurred, I think we should approach them with caution--they may want to enslave us or even worst--dissect us for the advancement of their science!!
Of course, given the level of tech they may have, we may have to listen to why they came and comply to their requests.
Given how humans treat other animals during scientific study, I'd hide.
Can assume any alien species getting here has a certian level of technology we can only describe with science-fiction. Interstellar travel is impossible for us right now, and for some centuries to come. Would take us, now, about 70,000 years just to get to Proxima 4.2 light-years away. Need many impossible things for interstellar travel like:
- suspended animation for the crew (can only carry so much air, food, water, etc.)
- kinetic and radiological shielding (micrometeor hyper-velocity impacts, and interstellar radiation, solar flares, etc.)
- unbelievably accurate radar to detect and plot courses around impacting objects
- propulsion and power systems so we can get somewhere worth going in a human's lifetime without their going insane and killing their own crew
- ship repair systems which can quickly and efficiently repair things that break duringt he journey whether by wear and tear, or accidents
Without these and other things you're not going anywhere. Anyone who shows up who did is WAY beyond us. Think they'd only recognize us as sentient by all the cities and roads. If they met one of us off by ourselves, there's no reason to assume they'd even recognize we're not something to pull the arms off of like children do flies.