These "races" as actual human ethnicities, are Tolkien-dependent racism, and are problematic.There's a long history of a lot of the races being very similar...
"The demi-human races are cousin species to humans." - Moldvay, B9
"All of the non-human or part-human races closely resemble humans in many aspects." - 1e PHB, pg. 15
"Similar to their cousins, the dwarves, gnomes are..." - 1e PHB, pg. 16
As far as 5e...
The 5e PHB's entire quote from the human point of view about halflings is: "It's hard to beat a meal in a halfling home, as long as you don't crack your head on the ceiling - good food and good stories in front of a nice, warm fire. If halflings had a shred of ambition, they might really amount to something."
About human's in general: "Everyone's second-best friends. Just as readily as they mix with each other, humans mingle with members of other races. They get along with almost everyone, though they might not be close to many. Humans serve as ambassadors, diplomats, magistrates, merchants, and functionaries of all kinds."