More immersive because I can relate to a human instead of a red demon furry

human is usually a solid choice mechanically, esp in d&d, and as a matter of course tend to have the most varied customization options (sure there may be horns for your tiefling, but maybe only a choice of 3 or they're locked to hairstyle etc)

not saying that's the case here mind, but those are some reasons beyond a committment to being boring

Because they want to make themselves or something less crazy? I really don't understand why everyone has to be a tabaxi, aaracokra, changeling etc nowadays. I like being a human or halfelf

In paper & pen RPGs I tend to design goofy personalities and attach them to boring standard race options. My friend who has been a part of the same group for 20 years loves taking pretty standard personalities and adapting them to fit the most bugshit insane race options he can find. We have had a lot of interactions where I - playing as a character that looks like the white guy from a diversity poster - go off on some rant about how I worship the concept of lies and illusions, and how I have written an entire manifesto about how all titles and human relations are manifestations of the holy concept of the ultimate lie, while my friend - playing as an entire swarm of 3" tall shadow goblins, with each hit point having an individual 1930s gangster name - looks for the most noncommital social democrat answer in the world. It's a good dynamic.

I still can't find any excuse to make a human look this boring in a video game though.