And they could also finally explore awkward first encounters, like how humanity met the Arcturians or any other races they might come across.
I don't mean make it a constant thing where a new race is discovered every other episode or something.
I mean the occasional episode. Make the encounters really difficult on both sides. If it's a friendly race, make it as if both are having trouble communicating to each other and maybe add misunderstandings that may need resolving in that episode.
Lots and lots of pointing at things to try and display a message.
And who knows if some of these aliens even communicate through sound or sign language? What if they are completely bizarre space cthulhu who speak by changing skin tones real quick?
Some interesting possibilities with that.
But like Winde said, the focus should be mostly on humans and within human space. Adding those aliens only for the sake of mystery and wonderment for us. Keep the universe huge and space travel costly even for other species so contacts would be rare, like a needle in a haystack rare.
The intelligent race we encounter the most should be the Predators and 99.9999999% of that should be hostile as it always is anyway.
I don't see why not make the series set during the Rage War? The first three seasons could cover the novel trilogy and the aftermath could be set after that. Rage War is set in 2692 AD, it'd be a neat setting for an Alien tv series as humanity has colonized 1% of the Milky Way galaxy. The novels already build so much world in them and that could transition in to a tv series.
Show explorers settling on new worlds and trying to get by. Show human rebels and anti-coporation terrorist groups fighting Colonial Marines etc. So much to do in a TV series!
And I'd love an animated series or even a movie so bad.