The other race options are fun too, but they just aren't as interesting or aesthetically pleasing as the humans. Human characters generate their personality through deed, rather than inheriting it through racial stereotypes. Just makes them a better blank slate to work with.
Short races are short.
Elves live too long, so your backstory if you start at level one is either you're a child or you've wasted hundreds of years not learning any practical skills for survival in the world you find yourself in, neither of which are appealing.
The 'evil' races struggle to fit into a lot of roleplay options, what with the racism and all. Especially in video games where the MC tends to manage favourable relations with all kinds of folk, human just fits better roleplaying that most of the time (although BG3 does a very good job in that regard)
Gith are too one dimensional (and it's the wrong dimension afterall)
Tieflings feel like they're trying too hard to be special. Hellspawn this and that. Same for Dragonborn....
Don't get me wrong though, I like to play non-humans for the right characters. Human is the one that fits the mould most frequently though.
Actually Gith aren't one dimensional, you probably missed the part where they had a civil war and splintered off into 2 groups, the militaristicand violent Githyanki of the Astral plane and the ascetic and monastic Githzerai of Limbo, there's also a secret 3rd group called the Pirates of Gith that later splintered off from the Githyanki when they didn't follow their fellow Githyanki into the Astral Plane.
