Inarguably, we have had no confirmed contact with Aliens.

Why ? Because practical deep space travel is clearly impossible.

Do the simple math :

Distance = Speed x Time

Distances are far too great, Speeds are far too slow and
Times would be prohibitively far too long .

Note that our fastest space probe so far is slower than light by a factor of nearly 27,000 .
So a one way trip to our very nearest neighbor Alpha Centauri at only 4.367 LY
would take 118 Millennia, where i Millenia = 1,000 years.

Even in the extreemly unlikely event that speeds could be increased to near light speed, times would still be prohibitively long.

Confirmation : It is very likely that sentient space faring species abound throughout the universe yet again no confirmed contact so far.