My reimaging of B5 would be like this.
There is no FTL, meaning B5 isn't only politically important it's the only major population center for .1 light years.
No time travel.
All prophecies are based on predictions of super computers, based in other solar systems therefore while highly advanced are incredibly vague due to time lag.
Due to a lack of FTL the time scale is much longer. The first ones and the shadows have been traveling the galaxy at sublight speeds for millions of years.
With all other alien races having been space faring for atleast 40,000 years.
There are no energy beings, however the biology of earlier species operate well outside our understands of biology.
There are only a small number of alien species. They are not rubber forehead aliens, and are much closer to starfish aliens.
With a more direct reference to the mimbari being aqualitic squid like creatures. With the cast system and dalen being far more similiar to avatars. The warrior cast are essentially genetically engineered super soldiers who are desinged to fight on earth. The worker class your traditional squid like creature, and the religions actually being avatars for the political class.
This would also put a huge amount of weight between humans being born with mimbari souls type idea.
The gnarn being directly lizard like, however very similiar to how they are depicted in the series. With a highly paranoid, anti social characterization.
The centauri, having birdlike features, including greater height, lean skeletal structures and inability to suffer earth gravity. With a language and communication style that is similiar to bird talk.
The point is getting far away from humanoid aliens unless there is directly a purpose.
Another added perk would be that concious transmission can occur over several light years.
So avatars functions as a necessity to galactic diplomacy.
Important themes, the hugely different cultures present on B5 would have dramatically different perseptions.
What are overly dramatic prohecies to the us humans would just be the weekly news to the Mimbari.
The chosen one from our perspective would be simply the whistleblower to theirs.
Space is a ecosystem and we are nothing but ants in little ant colonies.
B5 would have no direct influence on other ant colonies around the galaxy however would represent a cross continmation of species.