Technical you are all human and are bound by human aspects. What I mean is that even playing as another race you can only roleplay so far. If you are playing as a human it really is no different than an alien. Unless in real life you live in dnd.
The only difference is culture. Even humans have variety in culture. So from my perspective what is the big deal what race you play? How are dnd humans boring? They are better than regular humans and you have exciting opportunities to take part in and roleplay.
Seems to me the only boring thing is lack of imagination.
I think you're sleeping on another pretty massive, all defining aspect of what it means to be a type of creature; biology.
As a human I cannot roleplay a character who has a tail. Or wings and the power of flight. Or claws. Or fangs. Or tusks. Sure, I could... Roleplay a mutant human, but at that point is that even the same as playing a human?
This difference is the most extreme with the exotic races, though even the core races have some unique biological attributes a human would not. The elven lifespan and lack of need to sleep. The half-orc's cursed blood and constant drive to bring ruin. etc.
And these biological differences can have a significant impact on your character. Their body language and how they express themselves especially, but also in how they move and fight and sometimes how they go about solving certain problems with the unique tools they have. How your species reproduces can have a significant impact both on how they were raised and how they percieve their upbringing. A Githyanki or lizardfolk who are hatched from eggs and raised communally will see the very human familial unit as something strange and alien to them which produces interesting roleplay opportunities when forced to interact with one.
Then you have Yuan-ti, lizardfolk, kenku, etc. who all have unique psychological differences from baseline human that can radically alter the character's moral system, outlook on the world, and motivations. Again you could just roleplay a human with a mental illness to get something vaguely similar, but then you miss out on the communal aspect of the race. A lizardfolk isn't just a human sociopath. He was also raised by other sociopaths in an entire tribe of sociopaths with his own religion that extols sociopathic morals. That sort of background gets less and less easy to explain as a normal human being, but as a lizardfolk it all gets packed easily under race choice and comes with a variety of unique biological differences to further the human / lizardfolk divergence.
So yes. I'd say there is a significant difference between playing a human and an exotic race. And while you could make up a pretty insane, convoluted backstory about a human sociopath from a conclave of ex-criminals sent to a swamp who was then mutated by exposure to magic swamp gas as a baby to get a similar character you'd then need to add all sorts of additional bells and whistles to then play a subversion of the classic lizardfolk that wanted to explore their culture from a new angle.
Basically exotic races are an easy frame with which to tell exotic stories about characters who are so far removed from the "normal" human experience as to basically be alien.
