I believe 100% that there is alien life but don't ask me for proofs. It is just my intuition and logic that tells me we are not alone in this universe and never were. It would be very awkward for just us to be in the whole universe with so many planets and to be such a destructive specie as we are. I have even read about some theories according to we are made by aliens which might or not be true. I don't know. Regarding the question why haven't they contacted us already I can only say that if they haven't is probably that we can't understand each other yet and communicate properly or simply can't understand them or they might have contacted us already but the officials are not revealing such information. Either way can be true and there is another theory spreading that says some of the tech that we have might come from aliens as some sort of an exchange that they made with humans. Who knows? I do believe that humanity, or at least most of it, is not prepared to connect with and understand such civilizations that are probably way way more evolved than us not just technologically but spiritually and mentally also and it might shock us. We are still fighting over "black and white", over soccer teams, over which crypto is better or manifest an immense cruelty towards animals and that's not a sign of consciousness evolution. We might still need to mature ourselves before being able to embrace the encounter extraterrestrial civilizations. Or they might be already living among us, in human forms, or inside Earth as another theory is being popularized on the internet. Everything is possible in my opinion, but I don't have any proof for any of the suppositions I made. I can only say that I believe in the existence of such civilizations and believed in this thing ever since I was about 9 years old. That's how I think.
This is a pretty interesting question and I have always been fascinated with the thoughts of the existence of aliens. Obviously, my answer is... YES.
The universe is so vast that it's impossible for earth to be the only planet which has life. Of course, it's kind of difficult to give proofs, but I believe we had had contact with them. Maybe not us, but people in the early days.
How would one explain the illustrations in ancient caves or even in the pyramids which shows unusual entities? They must have seen them, so as to draw them. People got the idea of how they might look like or their lifestyle, perhaps because some may have experienced it in real life.
I know, people can be as imaginative af, but where do you think the foundation of these ideas come from?
I strongly believe that somewhere, in this vast universe, they exist. And for them, we are also life forms which are strange/unusual. We, ourselves, are also aliens to those life forms in other planets, in other galaxies, etc. scattered in this enormous and massive universe.
We really cannot say that there's only us in this infinite universe.