The Great wonderful world of Hilda is so great and beautiful with so many great creatures that exist but there is one being we had seen in the show and they had been living here long ago protecting earth but left many years ago and those are the Giants! But there is something these beings Know about that hasn't ever been know to others yet and that is The Giants know that there exist life on other planets!
So let's talk about this. In the show and graphic novels the giants are a race of creatures that are very old and have lived on Earth for thousands of years. According to the Wood Man's book "Giants of Old", they were the first things to live in the valley race of creatures that are very old and have lived on Earth for thousands of years. They would watch duty for anything that might attack the Earth from up above. Young giants mostly served as guardians, and their guard duty could be millennia-long duty. According to legend, Jorgen, the giant that Hilda came across, was the last guardian in giant history.
However, as time passed, space for the giants started to get smaller as humans appeared and built their towns to live in. Although the giants were not evil and held no malice towards humans, their size resulted in several accidents where they unintentionally crushed the houses of the humans. This caused the people to riot against the giants, forcing them out of their world: the valley. In the end, the giants were forced to move away from their home, their current whereabouts unknown. Some thought that the giants jumped as high as they could and floated off into space. Only a few giants remained on Earth Jorgen, who was still performing his duty as guardian, and the Forest Giants, who were the smallest giants and thus could hide in the woods.
Now in the graphic novels and show Jorgen had reunited with his love one Valfreyja and the two of them both flew into space. Now the giants had been protecting the earth but.... Why? It could mean one thing only the protect the earth from Big Threats that aren't from her one's that don't have respect for life or world conquer planets I'm taking about Aliens the Giants knew that there exist other life in the universe and they had see them before.
Also there are giants that aren't native to earth but came here as to protect it meaning that they would protect all life in the universe besides earth only. The Giants left because of the rise of higher small beings like humans so they had left earth and it's unknown where most of them had gone in the universe.
So we know Aliens exit in this world because of the Giants but dose this means humans know about this or are they unsure because we don't know if things like rockets or spaceships exist in the world of Hilda we don't know that yet.
But will we see Aliens in the Hilda like will this be explore in a future story or a future season of the show well we don't know and how will it be when they are introduce.
Maybe it could be Hilda encounter an Alien or Hilda and her friends somehow travel to another planet or it's an Alien Invasion (well okay Maybe not the invasion part because that would not feel right) but whatever it is Aliens will one day come in the world of Hilda because we all know they secretly exist because the Giants know they exist and they are not alone in the universe.