I disagree but I agree with those that say that most participants - including the GMs - are unable to inhabit alien things or even imagine them, and they usually have no desire to anyway. They generally play a race for the bonuses and, to be frank since I have no clearer way to explain myself at this time, for sexual self-identification reasons. They want to play something that they perceive as exotic and desirable and "cool" - whether elf or tiefling or goliath or whatever they think gives them their character that allure. This is usually associated with the race having a stereotypical body shape that is more like the human ideal than the human ideal, as well as being perceived as graceful, feral, wild, and dangerous.
But this isn't to say that the D&D races aren't alien if you think about it, or that they can't be really alien, it's just that there is a cost to making them alien which is the more alien you make them the less well your players will be able to play them. I do try to make my D&D races something sufficiently biologically distinct that they aren't just stereotyped humans but I don't really ever have my players ever grok the races. For this reason, I tend to use mechanics that strongly encourage a human-centric party, just because I tend to find human PC's better imagined and better role-played than non-human PCs.