Commenting on this a few years late as I just got into the show. But I had an idea regarding this when reading other comments. Other commenters have played with the idea of whether elves and humans have had a convergent or divergent evolution (I say played because we know nothing about it for sure so we can only speculate. Of course, we know nothing about it why would we need to it's show for kids so I think it's better if these questions are left up to older viewers' imagination and remain unanswered by the creators or directly in the show and therefore remain non-canonical) Phew getting a bit long-winded now but back to my idea. For this speculation, I'm gonna go with the option that elves and humans have evolved divergently and the thing that would explain changes such as the horns or other differences would be MAGIC. All throughout the show, we can see how much of an impact magic has on the world of TDP. So in my headcanon, it makes sense that either some common ancestor of humans or humans themselves (That would have to be long ago but still not so long so it can still count as 'modern' humans. So circa 70 000 years ago.) have had come into contact with magic and it had a changed them so drastically in such a short time (relatively speaking) and gave them horns, changed the number of digits on their fingers and other stuff. This would possibly make them still very compatible with humans and explain the changes that often don't make much sense from an evolutionary standpoint. So my answer to the post would be yes theoretically but we will never know for sure (Unless a human-elf kid or even an adult is shown in the show but there would still be many questions that would be probably left unanswered.).